Sunday, April 24, 2011

Happy Easter, everyone.

Like the title says, Happy Easter to everyone reading this blog, whether you celebrate the original intent or not.
Now, back to getting over the case of food poisoning I picked up........

Tuesday, April 19, 2011

Update on the .50 BMG

I have to admit, I've been busier than heck with school and getting things set up for the summer and fall semesters, so my builds have all suffered. I have gotten a little bit of work done on the trigger guard assembly I posted about last week, and I began construction on a new bolt body made of 1.5" OD DOM steel. I couldn't use the old bolt body, since it was constructed of aluminum. The bolt must ride over the hammer and reset it after each shot, so this would have quickly worn the aluminum down and ruined it.


 First, I finished profiling the trigger guard. I didn't take any pictures of this because I was in such a hurry to get it done I forgot my camera. However, after cutting the rest of the profile and rounding a few edges, I had a complete piece ready to mount on the .50.
This presented a new problem, as the receiver on the .50 is a piece of 2.25" OD tubing, and the top of the trigger group was flat. I didn't have 2.25" round nose endmill to cut the tubing radius, and a hole saw wasn't going to work, either. What I wound up doing was taking a piece of 2.25" solid 4140 round stock, 3/8" thick, and cutting it in half. I then milled the top flat, and centered a 1/2' endmill in the piece of stock. I then took the piece of 4140 and ground cutting edges on it. Then I heated it up until it was cherry red and I confirmed it had lost its' magnetic properties with a small magnet. Once it hit this stage, I held the heat on it for a couple minutes at approximately the same temperature. I then quenched it in oil to harden it, and once it had cooled a bit, I stuck it in my oven for 1 hour at 500 degrees. I can't say for sure how hard it is, but hitting it real good with a file did nothing but dull the file teeth. After this, I took a piece of 1/2" OD steel rod and welded it in place in the slot I had milled in the half moon shaped piece. I was able to cut a nice radius in the top of the trigger group with this on the mill. Here are some pics of the completed radius, though I could've taken better pics.




 Here's the completed cutter



Next up, I needed a way to mount the housing to the gun. I figured the easiest way to do this was with some 5/16" Allen head bolts. I didn't want the bolts to show, so I got an endmill out and countersunk the bolts into the housing. Some .5" OD cold roll steel stock, drilled and tapped to 5/16" served as nuts. The housing was mocked up in place, and the tapped pieces of steel were tacked in place very carefully.

The screws and tapped pieces of steel.

Setting up the housing to countersink the allen bolts

With everything welded in place, the trigger group was bolted on, and everything was test fit for clearance.


I have GOT to move that scope mount forward.



With that part done, I needed to machine a new bolt body that would work just like the old one, but would facilitate the use of a hammer instead of a striker. I started out with a chunk of 1.5" OD, 1" ID DOM tubing.



First, I threaded the inside to accept the old bolt head,

Then I threaded the outside so that the old 2" sleeves would thread back on.

Here's the new steel bolt body next to the old aluminum one. The one on the left is the new steel one. I haven't sanded or polished it yet, so it's still a bit rough. I also have to cut threads on the back end. I should have this done tomorrow. I hope to machine a new firing pin then as well and also mill out the bolt for the hammer to travel through and effectively whack the firing pin.

That's all for now, more tomorrow I hope.

Monday, April 11, 2011

Busy, busy, busy.

Have not had much time to do any work on my projects over the last couple of weeks, I have been way too preoccupied with school. I did, however, get in a slew of material that should allow me to finish the projects I have on hand and start on a couple more. I have a few more barrels laying around for some more rifles I plan to build, and a couple of semiauto pistol caliber smg's.



Last week, I decided I wasn't happy with the trigger housing on the .50 rifle, and since I really wanted the rifle to look better, I found a huge chunk of 5/8" steel plate laying around that would work for housing the chopped up Suomi trigger group I had to use with the striker system on the rifle. I really wanted to build something that looked better than the old setup, and milling out a housing would probably look better than just cutting and welding something out of sheet metal like the old one.

I started out with taking the cutting torch to the plate and roughing out a section I had approximated.

I took the plate after cutting it off and milled the top side flat.


Then, the plate was laid down and milled flat with a fly cutter.

 After both sides were milled flat with the fly cutter, I used the fly cutter to cut arcs in either end of the plate.

 Now, the bottom was milled flat


Now, for the fun part. Milling out the fire control slot. This took a while.


With the shortened Suomi group in it......


Now, about that pistol grip.....Oh, yeah, there's more metal to be milled down.
The finished trigger group, with sear poking out of the top.



Unfortunately, I made this for no reason. I tried to get the striker system working again with the new trigger group, and unfortunately, the striker system just wouldn't work right.
I was tired of screwing with the striker system anyway, so I threw my hands in the air and said to hell with it, right before I called Model 1 Sales and ordered an AR fire control group.
I'll save this trigger assembly for another rifle I plan to build.

So, I've got this fire control group sitting here designed for an AR rifle, all I needed was a block of metal to machine to fit a trigger group in. Speedymetals.com was good enough to have a sale on 1" thick aluminum plate sections, 11" long and 3.625" wide. That made for a good platform.



Add some Dykem so layout can be done...


After center-punching the holes, holes were drilled to .150 for the hammer and trigger assembly.


Next, the holes for the trigger guard were cut out. I didn't have an endmill large enough, but I do have a nice assortment of hole saws.

 After cutting most of the way through, I flipped the plate over and bored out the other side.


Next, I moved the mill table about an inch to the right and bored out the other end of the trigger guard.

I then milled out the slot for the fire control group to mock up the trigger and hammer. I haven't gotten to mill the rest of the trigger guard out, but that remains to be done tomorrow or the next day.
That's all for now, more in a bit.