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!