Wednesday, December 29, 2010

More on the Bill Holmes-ish .50 B.M.G. rifle

Been a couple weeks since I updated, I know. I have been pretty busy with the Christmas holidays,  with work (had to work the holidays, I don't think there have been too many holidays I don't wind up working. All part of the job.) and family in town and a whole list of other stuff to keep up with, I just haven't had much time to sit down and type up an entry.


Well, at my last update I had a more-or-less complete receiver sitting in my garage, a bolt that had had its outer diameter turned, a fire control group, and a few other odds and ends. One thing I lacked was a buttstock of some sort. I looked at the rifle for a few days trying to figure out what would work best and look like it fit the overall rifle.

This in itself was pretty difficult, because there are a number of stocks on the market that look good on most homebuilt rifles, such as the M4 collapsible stock, or the standard A2 buttstock from  a m16 or AR15. I had a couple of each of these laying around, and held them up to the receiver for mockup, only to quickly shelve them again. The 2.25" outer diameter of the rifle just didn't look right when paired up with the roughly 1.375" outer diameter of the collapsible M4 stock, and the A2 didn't look right at all.

I went over to Google and typed in "tubegun" to see what else was popular or available so maybe I could get some ideas. I found several that made use of AR15 and M16 stocks of many different manufacture, such as some seen on this site. In fact, those stocks look great on those tube rifles, but on my large receiver, an AR stock was just absolutely goofy looking. I feel that if you are going to build a firearm, it is important to at least try to make it look proportional.With that, the AR stock idea was shelved.

I couldn't very well use the exact stock method Holmes outlines in his book, as it is nothing more than a piece of tube with a flat plate attached. It really wasn't very flattering, although I realize his idea was more to have something utilitarian than pretty. After all, the buttstock does not decide whether the gun goes bang or not. After banging my head against the wall for a few days trying to decide what to do, I finally threw something together out of a few pieces of scrap material I had laying around. With the idea that I would build something similar to what Bill Holmes designed, but with a bit more eye appeal. I started with a piece of seamless DOM tubing that was about 1.375" OD, then cut off a 10" long chunk of it and chucked it in the lathe. I then knurled the tubing in the lathe after squaring off the ends. I had a small section of 4130 2" OD round rod left, so I bored it out for the DOM tubing so the tubing would sit perfectly centered in it, then fired up the welder and burned it in place. Once that was done, I cut a plate from .375" plate in the shape of an AR buttstock so that a buttpad meant for an A2 stock would fit and look right. I drilled and tapped 5/16" holes in the 4130 round stock I had previously welded to the DOM tubing, then drilled 11/32 holes in the end of the rifle receiver to match the drilled and tapped holes in the 4130. When the button head bolts were installed to attach the stock, it pulled the whole thing in tight, and the bolt would move all the way back in the receiver and bottom out on the buttstock, providing full access to the ejection port. It came together so well, there's no way I could have ever planned it.

Still, after looking at it, I still didn't like the large tube to small tube transition, and figured if I was going to use what I had thrown together, I needed to add a little bit to it. I dug around in the scrap bin and found some .5" 1018 round steel rod. I cut a good 14" section of this off, did some simple bending on it, then welded it to the bottom of the buttplate going forward to the 4130 round stock that fit into the receiver. I took another chunk of .375" plate and cut out a rectangular section that was welded to the bottom of the 4130 piece. I welded the .5" round rod to this to complete the buttstock for the moment. I then cut a slot in the bottom of the rifle receiver directly below the buttstock mounting area for this flat plate to slide in to place. This filled in the gap behind the AR pistol grip and the round rod on the stock I made. After all that, I cut up some .125" plate to fill in the gap between the DOM and the .5" round rod that the stock was made from. Bolted it all together, bent up a piece of that .5" round rod and threaded one end to attach it to the rifle bolt as a start for a bolt handle. I managed to completely botch this piece, (the bolt handle), but left it on for the time being, mainly so I could get a feel for the way everything looked together.
I threw some rattle can black spray paint on the parts, and threw it together to see where I stood. Ignore the bolts in the rear of the receiver, I had misplaced the button head bolts I bought for this purpose.




I'm still not entirely happy with it, although I do have a couple ideas how I can make it look a little better. I am going to bore 3 sequential 1.375" holes through the .125" plate I had welded in and then I will sand all the welds and other odds and ends down. If I am still not happy with it........

To hell with it then. I will just make it a pistol. A reaaaalllly looooooong pistol.

I got a bit farther than this with the rifle build before the holidays, but have had two separate things going on to take up my time, one concerning the .50 cal rifle and the other concerning another project waiting in the wings. More on that later.

Tuesday, December 14, 2010

Laziness finally kicked in.

Okay, so I've been a little busy the last few days and haven't had time to update my work on my .50 BMG build. My significant other has had a bit of a setback in her education, and I have been dedicating most of my time to helping her out and getting her to feeling better. The ball is rolling again, although I'd swear someone stole our original rolling ball and put an egg shaped one in its place, because that little S.O.B. doesn't seem to want to roll straight.


Most or all of the photos I will be throwing up here today are of work that has already been done, i.e. I already did the work a few weeks back but didn't think to take pics at the time. Part of my problem is simple; I use my iPhone camera to take most of my pics and video, but while I am in the garage, most of the time my iPhone is hooked up to a ipod speaker dock so I have some music to work to. Given that Steve Jobs is an idiot, the iPhone is not entirely compatible with the ipod dock, so taking the phone off and putting it back on the dock in order to use the camera involves a lot of touchscreen-button pushing. This is not something I want to do while having oily and greasy hands and fingers. So, some of the more menial things simply don't get photographed. Thankfully, for things like that, there is always google images and youtube. So, if you are just that set on seeing someone use a lathe tailstock to drill out a chunk of metal, you probably won't see that here. However, feel free to go spend several mindless hours of your time on youtube or google images. I toss images up more as a guideline to what is being used and how, and then a completed product.
Another part of today's post I should mention is that most of the metal parts pictured look very dirty and have odd black spots in random places. Part of this is a result of doing metal work, (especially grinding and sanding) in a closed area. That black soot gets everywhere. Another reason is that I have sprayed the parts with a couple coats of black rattle can spraypaint.
Why would I do that?
Simple.
Just about any kind of metal you can buy will have an oxidized coat on it, if not a layer of what I refer to as "hot roll" coating*. Below this coating are usually a number of pock marks in the surface of the metal, as well as some corrosion and in really bad cases, corrosion to the point of surface pitting.
I spray black spray paint on the surface so that I know how far down I have to grind, mill, and/or sand until the surface is smooth enough it can be polished.
A lot of the metal I used to build the trigger guard and buttstock area was old scrap I had laying around, and as a result most of it is pretty pitted. There are also a number of grinding scuffs wherein I ground the welds I could get to. I will have to go back and sand these areas with block and some heavy grit paper and progressively lighter grit paper in order to flatten the whole area and get it looking right. Yes, this is a PITA. But, I want it to look good.
 So, with all that said, realize that most of what nastiness you see is there for a reason. Don't crucify me just yet.
On with the show.


I suppose it is worth mentioning that the original Holmes design uses a striker system of sorts, wherein a spring loaded firing pin is held captive by a sear when the bolt is pulled back, in lieu of a firing pin that is struck by a hammer. As such, I needed a trigger assembly that did not rely on a hammer assembly, such as that that many other .50 manufacturers use. I don't know for sure, but I think most of the .50 manufacturers on the market simply use a AR 15 grip, trigger, hammer, spring assembly, etc. Nothing wrong with that, of course, as it seems to work just fine. However, I'm building my rifle on the cheap, so I originally thought I would just machine my own trigger and sear system to save money. Well, as the title of the post says, I got lazy. Turns out I had a complete trigger assembly laying around from another project that would work just fine.


This is a part to another project I am building (soon to be posted about!). It originated in an open bolt tube gun (bonus points to anyone who can figure out what kind) and given that the open bolt system and a striker system both rely on a sear to release a spring loaded bolt or firing pin, this turned out to be an obvious, easy choice. I hated to put anything on the gun I didn't build, but the price of the metal necessary to build a completed homemade assembly was almost the same price as buying another one of these surplus trigger groups (about 10 bucks), so I just went online and ordered another open bolt trigger group. Yes, I'm lazy. So lazy I didn't want to carve out a new trigger, sear, and safety. So sue me.

So, the trigger/sear assembly was ready as soon as it shipped to my house. Without any pressure against the sear, the assembly worked very smoothly with no grit or unevenness to the overall pull. Even with pressure applied to the sear, the trigger pull is just slightly creepy with a decent break. Time will tell how it works out when the captive firing pin and spring assembly are being held by this sear. Overall, I like it, with a notable exception being the safety. Clunky and ugly are the best terms I can describe the safety with. I did, however, have to cut a screw tab off the rear of the trigger group and drill the assembly for two different pins that would secure the trigger assembly to the rifle receiver.
It should be mentioned here that I really did not care for the trigger group that the Holmes plans outline. The outlined assembly in the Holmes plans do not provide for what I consider a 100% secure sear assembly, even though I know for a fact that his provided planned assembly does work, given the number of these rifles that have already been built. The two assemblies (Bill Holmes and the open bolt SMG trigger assembly) both work the exact same way, but the SMG assembly is even simpler in design than the Holmes design and the sear seems a bit more reliable at first glance. Again, I know the Bill Holmes design works and I'm guessing works well, given the number of rifles built using that design. I just liked the simplicity of the one I used and the cost. Again, so sue me.

So, now I've got a trigger assembly. Great. I've got something I can run around the garage with and make "pew pew" noises with. This is fine, but what I really wanted is the trigger assembly mounted to a receiver (so I've got something I can shoulder and run around in my garage, pointing  and making "pew pew" noises). Albeit it wouldn't be as cool as this "pew pew".
So, I dug around in my scrap metal bin and found a two foot long section of some .125" thick 2" wide hot roll steel plate. After taking some quick measurements as to how tall I needed the strips cut in order to let the sear of the trigger group protrude into the receiver at least 3/16", I threw some black spray paint on the steel plate, used a scribe to outline the cuts needed, then took a cutoff wheel in a grinder and cut the plate out. I also added an extra 1.25" to the overall length, more on that in a second. I considered cutting four total plates to make a rectangle, then just decided to bend the metal in a small metal brake and only have one weld to make. I try to save myself a little welding and extra work when I can......

I threw the trigger group in this steel rectangle I had made and put the trigger group in place, clamped it all together, and drilled it for the pins that would hold the trigger group into the rectangle. After those were drilled, I cut a piece of 3/8" plate to weld in behind the trigger.


This plate was thick enough to mount my next example of laziness to.





I could have made a grip out of wood, but I already had one of these AR grips laying around on a Smith&Wesson M&P 15 lower I've had that is in need of an upper. Why complicate things when you're feeling unambitious?

The final product mocked together



It's a little rough right now, but a little sanding and polishing will fix that up.

Next up, I had to cut a slot in the bottom of the receiver for the sear to protrude through. This required a bit of filing and sanding to get cleaned up in preparation for the striker assembly that is forthcoming.

Annnnnnnnnd, the whole thing welded together........





Now, throw a bolt into the mix with a makeshift bolt handle.




So, the main body of the gun is together. Just need a scope mount, buttstock, firing pin, final bolt handle, and some miscellanea. Still doesn't look like much in these pics, but it gets better.

Stay tuned..........


*When you buy normal, non-alloy steel from your local steel yard, you can buy several different shapes (i.e. round rod, bar stock, plate, and sheet) in either "hot rolled" or "cold rolled". The hot roll is generally cheaper, but is not as clean and is usually not precisely sized. It is as it comes out of the steel mill, with a really nasty black oxidized coating on it. Cold roll, on the other hand, is extremely clean, has no black coating on it, and is usually within .005 of what size it should be, sometimes even closer. Cold roll costs much more than hot roll, though. Hot roll steel is simply the steel after it was pressed into a mold or poured into a mold, pressurized while still somewhat molten and allowed to cool, whereas cold roll steel is steel that was poured and allowed to cool before it was run through a series of extremely high pressure rolls or into a high pressure mold. It is formed under extreme pressure while still cold, or at least at non-molten temps. More info on this can be found here. Now, this only covers basic run-of-the-mill (no pun intended) steel, there are many kinds of steel out there beyond these.

Wednesday, December 8, 2010

Laughing is good for the soul. I hope.

Some of the kinds of tools that see a good bit of use in my tool collection are mill files. I have a good number of different files, each for a different purpose. Some are good for heavy stock removal while others are good for light feathering of material prior to sanding and polishing.

I had welded a seam on some 4130 stock earlier, and had chucked the assembly in the lathe and turned down most of the weld. I didn't want to go too far into the parent material with a grinder or the lathe bit, so I saved the last .05" or so for filing, starting with a heavy mill bastard and progressively working my way up to finer teeth grades of file before finishing with 80 grit sandpaper.

Well, I had been using my heavy mill bastard file on another project (soon to be posted about), and I thought I had left the file over on the workbench by that particular firearm project. When I shut the lathe down to find my file, it was nowhere to be found. I continued to wander around the garage in search of my tooling for almost half an hour when all of a sudden my phone began ringing. I picked it up and started conversating with a friend of mine who had some firearm related questions. After answering his initial questions, he inquired as to what I was doing at the moment.

I sat there thinking for a second trying to think of the best way to explain it to him, when I finally answered, " I'm looking for one of my tools, but all I keep getting is a 404 error: File not found."


About the same time he recovered from his laughter I found my file, laying right next to the tailstock of my lathe. Apparently I had put it there in preparation for the lathe work I had planned to do, and forgotten all about it.

Tuesday, December 7, 2010

50 cal barrel

Here's a link to an auction on Gunbroker that has a barrel identical to the one I used on my rifle.


http://www.gunbroker.com/Auction/ViewItem.aspx?Item=204292323

A little spendy, but a good place to start.

Machining the chambering area.

On to the next piece of the puzzle, the threaded chambering piece, or "barrel extension", that attaches to the barrel.

(I think Bill Holmes refers to this as the barrel extension in his book, as it is not the actual "chamber". I couldn't think of a decent term for this piece, so barrel extension is fine. Whatever.)

So, yet again I chucked up some more of the 2" diameter 4140 solid round stock and began the arduous task of parting it off in the lathe. Trust me when I say, parting off 4140 round stock with a HSS cutoff blade on an old Logan lathe is a real PITA. That took me at least a couple of hours or so.
Thankfully I have a new lathe lined up for purchase, and as soon as the money comes through in the next few weeks, I should have a much newer and larger lathe.
So, once I was done standing there and listening to the squeal of the metal being parted and the roar of the back gears on my lathe, I had a >2.5" long section of 4140 ready to be machined. When I was done parting the material, I faced off both ends of the section of solid round and began the next long task, boring the whole thing out to a 1" inner diameter.

I don't know who coined the term "boring" to describe drilling out large holes, but they were right on the money with that particular word. Geez, was that boring.

And messy. That took a lot of cutting oil for the drill bits and HSS boring bar.

I didn't bother taking any pictures of that process. A 1/8" bit to start, and slowly worked my way up to a 1" drill bit to bore through the whole thing.

 Once I was done with the drilling, I had to bore one side out to 1.3" inner diameter and 1.75" deep in preparation for threading.



Now, the inner .75" was bored out to 1.5".

Next, the outer 1" of that side was now bored to 1.3" and was then threaded to 8 t.p.i.





I cannot stress how difficult this was to do, doing a smaller bore and thread on the outside with a larger bore on the inside. It also had to be measured and cut precisely in order to get a round to chamber properly. The largest reason for the smaller threads was because the M3 barrel I bought was already threaded on the chamber area, and it had the most unconventional sized threads I have ever seen. In retrospect, I wish I had had a normal barrel blank to turn instead of the surplus M3 barrel I bought. Oh well, live and learn. It seemed to work out just fine in the end, however it took quite a while to do this.

The bored and threaded piece.



Next, this same piece was reversed in the lathe chuck and a dial indicator was used to check for runout to make sure I had faced it off properly. After I was certain it was, I removed it from the lathe and took it to the workbench for some paperwork.
Paperwork?
Yes. Paperwork.
As in, drawing a section that mated with the face of the bolt I had previously machined in my cad program, printing it out, and gluing it to the other side of the piece I had just bored and threaded.





You can see that there are inner and outer lines. I used the outer lines as a guide for a punch. The dashed lines were there to represent areas that did not need cutting.
I went back with a punch and outlined all the areas to be machined, and after that removed the paper in preparation for machining.
All the punch marks in the corners and inside edges were drilled with a 1/16" bit first before clamping the piece in the mill. I then took a 1/4" four flute endmill and trimmed the rest of the inner "ear" area out. As you might have guessed, the inner circular area was the 1" bore from earlier, so all that had to be milled out was the inner "ear" areas. These "ears" took several passes with the endmill, and when I was within .01" or so of the edge limit, I stopped milling. I then took a bastard cut file and finished the part until the bolt snugly fit into this piece.

Once the bolt fit snugly in place in this "barrel extension", I threaded the whole assembly on to the barrel.
Here's the extension in place on the end of the barrel with the tapered barrel retainer in place as well.



Now, here is the entire assembly including the bolt in place. It is a very, very snug fit.


It was a heck of a lot of work to get to this point, but it was well worth it to see that part come together.

Notice that the bolt only has the outside machined, and I will say now that there was a lot of work involved in getting that particular item drilled and bored as well.
With that out of the way, its getting late here and it's time for me to call it a night.
More later.....

Sunday, December 5, 2010

Wednesday, December 1, 2010

Receiver fun

Now that we're past the rest of the previous noise.......



On to the receiver!

Honestly, there wasn't a whole lot to the receiver. Let me begin by saying that the overall length is arbitrary, well, as long as it isn't any shorter than say, two feet long or so. Any shorter than that, and I would be concerned about having the muzzle blast a bit too close for comfort.

The Bill Holmes guide calls for a three foot long piece of 4130, 2.25" outer diameter and .12" wall thickness. This gives a .005 inner clearance when a 2.000" inch piece of 4140 is used for the bolt, which has shown to be more than sufficient for clearance. The bolt will move back and forth and turn freely, especially when given a little bit of oil to lube things up a bit.

Anyway, I originally bought a 3' section of 4130 for the receiver. I had no issue with a 3' long receiver at first, until I realized I really didn't like the overall look of the gun as the original plans outlined. I finally got around to photoshopping the whole thing and then I realized I preferred the receiver right around 28" long. So, back in the lathe the whole assembly went, and I parted off about 8 inches of receiver. I did a rough reassembly of the barrel and receiver blank tube and decided I was pretty happy with the overall length and appearance of it.

In the original plans, Bill Holmes outlines a number of slots that are to be cut into the end of the receiver, mainly for looks. I liked the slotted look on his receiver, but affixing a large (2.25" od) tube into my milling machine is a bit of a pain, as I don't have a vise that can effectively grip a tube of that diameter. I can do it, but it takes a heck of a lot more work than I was interested in doing, given that the whole slotting thing is arbitrary, and really is done just for looks. After mulling the whole thing over, I decided to just drill a series of holes in a similar manner as the slots were supposed to be milled.

I took the original drawing from the Holmes manual and got the necessary dimensions from it, then opened up my copy of Deltacad (my favorite CAD system) and redrew the whole receiver and measured out the series of sequential holes that I wanted. I first inserted the .5" holes in the drawing where I wanted them after calculating the given distances to make sure everything was even and equidistant, then I put a smaller circle inside the center of the .5" hole so that I would have a place to center a punch.
After that, I measured and illustrated in my CAD drawing where the slots for the bolt handle and the bolt access needed to be. I also made a set of marks in these, as I didn't want square corners to all the slots I had to cut, I wanted radiused corners instead. So, I guesstimated what radius  I wanted and from there marked the center of that so I could drill a hole and complete the inside of that corner.

Once I had all that done, I printed the whole thing out at a 1:1 scale, which gave me about 4-8x11 sheets to join together on the receiver. I then took the receiver and sprayed 3M spray-on adhesive on the receiver and on the printed out drawings. Here I made a mistake, although not a crucial one. When I applied the drawings to the receiver, I managed to misalign the ones with the series of holes to drill. I didn't notice this until after I had drilled them. Dammit.
Thankfully it isn't off by much, and it really doesn't make much difference. Thankfully it is not altogether too noticeable, but I know it's there, and it irritates me when I pick up the rifle and see it.

Once the template was in place, I got a punch out and marked the center of all the holes to be drilled, both the series of sequential holes (speed holes, as Homer Simpson calls 'em), as well as the holes in the slotted areas' corners.

Next came the fun part. Drilling a LOT of holes.
By the way, Harbor Freight is good for a handful of things, including cheap prices on 10 packs of HSS drill bits. I picked up 2 packs of 1/16", 1/8", and 1/4" drill bits in anticipation of this process. Glad I did, because HSS drill bits do NOT last long against 4130 tubing, even with ample cutting oil.
I started out by clamping the tubing to the mill/drill table and making sure it was centered for the drill bit. (Side note here: clamping the tubing to the table in preparation for drilling is not hard. Getting it clamped to the table or the vise securely enough to be milled is something else entirely.) I have a few different centering drill bits that are normally used in a lathe to drill a centered hole in stock that is to be mounted between centers and turned. I used one of these bits to do the initial drilling to mark the hole, then switched to 1/8" bits to finish the hole boring. Once that was done, I switched to a 1/4" bit to enlarge the hole, then a 1/2" bit to finish the job. I have a small carbide tool that is used for cutting and clearing any shavings that remain from drilling holes in metal, so once everything was drilled I went ahead and trimmed out any remaining shavings.

This is what I was left with



And, after adding a barrel and barrel nut for mockup,



I also drilled holes about 3" in front of the chamber area in which the tapered barrel retainer would reside. Twelve 5/8" holes were drilled in two rows of six holes around the circumference of the receiver. The tapered barrel retainer would be plug welded through these holes once the chamber and a handful of other things were machined and set in place. However, that is for another entry......

Saturday, November 27, 2010

Metals used and a few vendor links

Due to a handful of questions and comments made by a few friends during a B.S. session the other day, I thought it might be useful to throw in some information about the material used to build not only the Bill Holmes .50 BMG rifle, but a number of other firearms.

Most of the material used on the .50 so far has been 4130 chromoly or 4140 chromoly. A decent write up on the properties of chromoly can be found here.

I guess it should be mentioned that I am NOT building this rifle, or any functional piece on it (aside from the buttstock and the bolt handle) from 1018 steel. Everything on this rifle is built from manufacture certified 4130 and 4140. This is not something I take lightly, given the unreal amount of pressure present in any rifle round, especially the .50 BMG.
This rifle, upon completion, will be taken to a professional for hardening. I would LOVE to have the capabilities to do this in my garage, but the reality is that this is one thing I feel better about taking to a professional. I have hardened steel parts before, such as extractors for AK's and smaller things of that nature, but a whole rifle is beyond my capabilities. I have no problems admitting that.

I have seen a handful of other homebuilt rifles finished and working that were based on the same basic design I am using.Were I purely starting from scratch and designing everything myself, then this might well be a dangerous proposition. I see no reason why anyone with a handful of tools and access to a mill and a lathe and appropriate materials could not build this rifle or any like it.

With all that said, I have a policy of giving credit where credit is due.  From that, I should throw in my personal recommendations to the following metal suppliers, all of whom deal in small quantities of just about any kind of material you could think of.

1. Aircraft Spruce and Specialty. I highly recommend this company, as the price was right, the shipping was fast, and the service was great. I bought the 4130 tubing for my receiver from there. I'm no shill, just a happy customer

2. Online Metals Great service, prices were a little steep on a few things. Decent shipping rates. Again, I'm no shill, just happy enough as a customer that I have no problem recommending them to others. Metals can be purchased by the foot and by the inch.

3. Speedy Metals Pretty much the same as Online Metals, although prices are a bit lower at Speedy Metals. Great service, fast shipping, etc. They gifted me with nothing except a good experience.

Pretty much any metal stock needed for anything I can think of can be acquired from one or more of these three suppliers.

So far, without the price of the barrel, I have about 125 bucks invested in the rifle through the metal I have purchased through these suppliers. If I recall, I paid about 225 for my M3 barrel, so I should have less than 400 bucks in the rifle by the time I am done, prior to purchasing optics. Of course, that does not cover lathe cutting bits, drill bits, welding gas, grinding wheels, end mills, and a few other odds and ends (firing pin springs, fire control group parts, etc). So, I guess I'll be out close to 500 bucks before optics.

For what it's worth, I plan to do another update in the next day or so over more of the build, and I may actually toss up a pic of the assembled rifle if I can get some batteries for my camera. Most of the work on the rifle has already been done and most of what I have posted up is actually stuff I did a couple of months ago.

Stay tuned.........

Wednesday, November 24, 2010

More machining on the bolt......

Okay, so I had already turned down the outer end on the bolt in anticipation of machining the locking lugs on the bolt. The original Holmes design calls for machining 3 male lugs on the bolt. I have seen a few designs, such as the serbu BFG.50 that use only two lugs. There doesn't seem to be a whole lot of difference between the two, at least not when it comes to functionality. So, I went into my CAD system and sketched out the lug system, printed it out and glued it to the bolt face. From there I took a punch and outlined all the areas that needed to be milled out.
I had an old lathe headstock laying around that was still functional but had been replaced due to age. I made a set of mounts for the lathe headstock that would allow me to bolt it to the milling table. The headstock of the lathe had a locking stud and with that locking stud there are indicator holes every 6 degrees. I set the bolt up in the chuck on the old lathe headstock and used that as a dividing head of sorts. From there I just supported the opposite end of the bolt directly below the area being machined and then went to milling it out alternating between a 1/2" cobalt end mill and a 1/4" carbide end mill.




No, the wood is not what's supporting the bolt in those pics. There's actually a set of machined steel blocks under the bolt supporting it.

After a couple hours of cussing and milling, rotating and milling, and a whole lot more cussing, I had a more-or-less machined bolt. I wasn't real happy with the finish the end mills left (the cobalt one was getting dull and the carbide one was chipped pretty badly.), so I made sure and left about .01 inch of material on the area being machined so that I could fine tune the bolt with a file and some sandpaper. That was an exercise in insanity all by itself.



For those who are looking closely, you can tell this was indeed built in my garage, as you can see my weedeater in the background of one of the pics.

And.......after a short trip back to the lathe to take a couple thou off the outside of the bolt, this is what it looks like so far...
More on the bolt later. For now, it's on to the chamber and the actual tube receiver.....

Blog has been updated a bit

Finally made some additions and changes as well as an update has been added.
More updates to come.....

Machining the bolt on the .50

I suppose an update is in order.
I had been working a steady schedule with my employer right up until the middle of September, wherein I had to work a normal "banker's hours" schedule. Between work and college classes, I would oftentimes get home from work/class too tired to work on any of my side projects, let alone blog about it. Now I am back on my normal schedule and actually have time to do my normal thing, which includes tinkering in the garage.

So, as of my last update, I had machined the tapered barrel guide, turned the barrel down to the diameter I wanted and threaded it for a muzzle brake and a barrel retaining nut. 4140 is pretty good stuff when it comes to machining, which is good because by the time I got done machining the barrel, barrel nut, and tapered barrel guide I had a HUGE pile of chips and curls left over. Next up was machining the bolt.

I started out with a 2" piece of 4140 solid round stock about 9 inches long, chucked it up in the lathe between a live center with a steady rest supporting the bolt material as well. I started to machine the area that would contain the chamber lugs by turning the last 1.75 inches of the bolt down to a 1.5" outer diameter.




I then measured an inch back and machined that 3/4 inch long section down to a 1 inch outer diameter.


Next up, I needed to machine the lugs on the bolt so that when a round is chambered and fired, the rifle doesn't blow apart. This needed to be machined on the milling machine. Despite my best efforts, I had to do some final finishing work with a file and some sandpaper. :\
More on this in a bit.....

Welcome Saysuncle readers

Holy crap!!
An Unclelanche!

Haven't updated in a few weeks because of work wearing me pretty thin. Guess I will have to update now, since the rifle is almost done.

There's not a whole lot of WECSOG to be seen here, at any rate.

Saturday, October 9, 2010

More on the homebuilt .50.....

I haven't had too much chance to update this last week or so due to a really oddball work schedule. When I've had the time to sit and type, I really haven't felt like it due to being too tired. So, despite having had most of these pictures around for a few months, I haven't had either the time or the ambition all at once to put them on here. No matter, says I. At this stage in the build, I have about 2/3 of the rifle complete, but I am posting each stage as I get time and energy. I might also mention the fact that my college classes take up a lot of my extra time, on top of working, keeping up with a family, and working on other projects like bookshelves and various other things around the house.

So, this time around I have a pretty simplistic piece I had to machine. This is nothing more than a piece of 2" 4140 solid round stock bored out to 1.5" and an internal 4 degree taper turned on the lathe. This is to fit over the tapered area above the chamber I mentioned in my previous post.
The purposes of this piece are:
1. Center the barrel in the receiver tube
2. Allow the barrel to be pulled tight and solid inside the receiver tube when it is eventually welded into place inside the receiver.






Nothing too special, but it still took a while to make, considering I am working with a 70 year old lathe that was cobbled together from two different lathes (I think) and an assortment of drill bits and boring bars.

Next up, I finally got around to cutting and drilling the receiver for the soon-to-come bolt, chamber, and barrel.

Wednesday, September 29, 2010

The start of a lengthy project



I was perusing GunBroker one day after reading up on the Holmes .50 cal, and came across a surplus M2 barrel. The Holmes .50 build plans suggest starting off with a simple barrel blank from any barrel manufacturer, but mentions that a surplus barrel from a M2 might be the easiest path to get started on. The surplus M2 barrels are already chambered and threaded for attaching to a receiver. I thought this to be worthwhile advice, and without any other further issue I bought the surplus barrel off of GunBroker for a couple hundred bucks.

A few days later, the barrel showed up in the mail. A quick measurement or two and it was off to the bandsaw to trim the barrel down to a size I thought would look at least somewhat proportional. I had decided early on that I didn't want to build the receiver as long as was suggested in the Holmes plans, so I wanted the barrel to look correct in relation to the receiver. So, I sawed the barrel down to about 23 inches and chucked it up in the lathe.



I turned the outside of the barrel down in sections, due to it having a really odd profile from the factory. The Holmes plans suggest a 1.75 major OD for the part of the barrel that fits inside the receiver, and then a 1" major OD for the visible part of the barrel. I couldn't achieve the 1.75" dimension with the surplus barrel I had, so I turned the initial diameter down to 1.5" and then turned a small shoulder halfway down the barrel to 1.375" for the barrel retaining nut.



I did stick to the 1" diameter for the remainder of the barrel. In retrospect I wish I hadn't done this, I kinda wanted to flute the barrel but there really isn't enough meat to the barrel to do this. I turned a small shoulder on the muzzle of the barrel and prepared the barrel for threading by machining a tiny taper on the end of each part to be threaded. I have yet to crown the muzzle, but am waiting to do that until a later date.

After I got the barrel turned to the diameter I wanted, I turned a 4 degree taper on the portion of the barrel directly above the chamber. The barrel was 1.7" at this point only, so I turned it down to the 4 degree taper over a ~2" length. Once the taper was finished, I tried to set my lathe up to turn some threads only to find that whoever had cobbled my lathe together had made some really odd modifications to the change gear set up. I tried to get the gears setup for threading 12 tpi, but wound up breaking the bushing assembly on the threading assembly.

A few weeks later, I had the threading setup back up and running on my lathe, and got around to threading the barrel, finally. The chamber of the barrel comes threaded from the factory, but it is not threaded even close to what Holmes suggests. Holmes suggests a 1.5" diameter threaded to 12 tpi, but the surplus barrel came with a 1.44" major OD 1.3" minor od threaded 8 tpi. This was only mildly problematic, but I got past it. Anyway, I finally got the muzzle and the barrel nut area threaded.




When all this was done to the barrel and I still had the threading gears set up on the lathe, I decided to machine and thread the barrel retaining nut. I had purchased a good 2 foot section of 4140 steel round 2" in diameter and a 6" section of 4140 round 2.25 diameter. The barrel nut was machined from the 2.25 diameter round stock and parted off on the lathe. For those of you who haven't ever done it, I highly suggest a carbide parting-off tool for working with 4140. I used a HSS blank and honed it to the correct shape, but still had to engage the lathe back gears in order to keep from melting through the cutting bit. 4140 is pretty freaking hard stuff.

With the barrel retaining nut machined and threaded, I knurled the outside diameter so I could get a grip on it for tightening down the barrel.


More later.....

Sunday, September 26, 2010

The Bill Holmes .50 cal rifle (sorta)

A while back, I came across an assortment of different articles about gunsmithing and different home built firearms. After digging around a bit, I read about something called "The Holmes .50", wherein a gunsmith by the name of Bill Holmes had originally made a video detailing his build of a very simple tube receiver .50 caliber rifle. He initially only made the video, but was inundated with requests for printed instructions on how to build the rifle from the video.
I found this fairly appealing for a number of reasons, not the least of which was that I don't yet own a .50 BMG chambered rifle. There have been a number of attempts to ban rifles in this caliber, but none have been successful so far, save for California's ban. What a ban on the .50 would actually accomplish, I can't fathom. As soon as a ban were enacted, I'm sure we would see the creation of a .4999 cartridge to replace it with. However, like any of the other laws and actions of the anti-gunners, not only would a ban be pointless, but would certainly follow the law of unintended consequences. With that said, I wanted to add one to the safe prior to any ban.

Yes, I know that the Heller case recently outlined my right to keep and bear arms and then the recent McDonald case enforces that right against the individual states. However, I also know that many states, municipalities, and several subsects of the federal government have misread, misused, and abused the clear intent and verbiage of the founders as it concerns the 2nd amendment and pretty much anything else that might somehow empower them. I believe that the battle for our rights is far from over, and I do not trust in the government to keep me a free man. I believe liberty is dependent on each and every one of us.
Needless to say, despite recent court rulings, I am not holding my breath when it comes to the federal government recognizing my rights. Thus, I have no problem attempting to build the big .50.

Many of the .50's on the market start out in the $2000.00 and up range, and most big name brands (Barret, Armalite, etc.) can break the 8k mark for the semi-auto models. Rolling my own has worked out to be much cheaper than any of the above.
Semi-auto is a bit beyond my reach at the moment when it comes to such a high-pressure round, so it would seem that a single shot, bolt action is good enough from a build perspective and from a cost analysis.

Another build of the Holmes .50 was outlined here. I don't know how old this website is, or if that builder got any farther with the rifle, but they sure did some very nice machine work on that rifle.

Next up, gathering parts and tooling......

Tools, tools, tools. A necessary thing. No, not the ones in Congress.

Let me start off by saying that I am not a professional. There is nothing even remotely professional about anything I do, save for my actual, well, profession. I build what I build and do it how I do it to entertain me, not to impress anyone. I don't care if I don't do it like the pros do it. If I did, then this wouldn't be merely a hobby.

I took metal shop for 3 or 4 years in high school, and concentrated mainly on welding. I taught myself how to oxyfuel weld when I was about 12. My dad brought home a torch rig he bought from a friend, and neither one of us knew how to use it. I set out to find out how, and after a number of mishaps and burns, I figured it out. From there I bought a small stick welder and learned how to use it. By the time I reached high school, I was a decent welder but knew nothing of machine work using a milling machine or lathe. I got into metal shop and learned the finer arts of MIG and TIG welding, and for the first time in my life, got to use a milling machine and a lathe. We had several Bridgeport knee mills, and a few 12"x36" tool room lathes, a few 16"x72" lathes, all the way up to a 36"x120" monster of a lathe. I never saw the big one running, and don't have the slightest clue what they had it for. I never knew how good I had it while in that shop.....

Fast forward about 10 years, and I had amassed quite a few tools, a couple of MIG welders, a plasma cutter, a huge sheetmetal brake, sliproller, and sheetmetal shear. I had also built my own cnc plasma cutter. I was in the market for a lathe for a while when I was contacted by someone who needed help building a cnc wood router. I made a 3 hour one-way trek to his house to help him with a few odds and ends on his cnc router. While I was there, this guy asked if I wanted a lathe. I went around to his tool shed where he had the old lathe. He had gotten it second or third hand and had used it to make furniture pieces but really had no use for it anymore. I was the new recipient of a late 40's vintage Montgomery Wards PowerKraft (Logan) lathe. For some reason, someone had put a Atlas lathe headstock on it.
I turned a number of parts on it, and used the heck out of it. Somewhere down the line, I sold the lathe to a friend, as I was moving into an apartment and had nowhere else to put it. I moved into a house about 6 months ago, and got the lathe back from my friend who had done literally nothing with it.
Around tax time, I found a Rong Fu model 31 mill/drill on Craigslist for 500 bucks. A friend of mine picked it up for me and delivered it to me.
I had kept most of my other tools from my previous endeavors, so I was set in that department.

So, I have the main two components for building just about anything I desire. Well, within reason.

Next up, I will start to detail the build of my .50 cal rifle. Yes, that was my first gun to build, but the design is simplistic enough I haven't had too many problems in the build. Yet.

Blogging. What a weird word.

I'm not much of one for writing. I am blogging simply because I like to have a public archive of different guns I am building. I tend to read other blogs more than I write, and I am usually too busy with my education to write a whole lot.

I am an engineering student, and am considering a degree in Applied Physics as well. I enjoy designing and building things with my own two hands, as opposed to simply going out and buying them. The limitations of that would be things like end mills, drill bits, etc.

I have been collecting and shooting firearms for quite some time, and decided recently to get in the hobby of building them. It only made sense, given my background, and it is something I find relaxing and very rewarding.

I may indeed blog about political items that catch my fancy, but it would be infrequent at best should I actually chose to do so.

Anyway, perhaps there is something on these pages that may help others out, and if nothing else, serve as eye candy for others.
Enjoy!