Wednesday, May 23, 2012

Some small project updates....AND A NEW GUN (YAY!!)

I've been pretty busy with some personal things, but I've been swamped in the garage with projects. A lot of you have contacted me about machining parts for the Suomi parts kits, and I've been amazed at the sheer number of people who wind up here looking for parts, information, or both. I've got several complete parts kits sitting here, as well as a few bolts and shrouds to be modified. For example, here is a stock barrel shroud next to one that I modified for a fellow gunny who stumbled across my blog. I modified it exactly like the one I made on my first parts kit build last year. It works well, and looks pretty good. Applying some Duracoat to it would make it look great, and it would blend in to the untrained eye. Too bad we have to live with our stupid NFA laws wherein a 16" barrel is okay and safe to own, but a 15.75" barrel is altogether unsafe and requires a 200 dollar tax and lots of paperwork.



Something else I have been working on of my own is the bolt carrier to my .50 BMG rifle. I took it to the Dallas blogshoot and had a blast (literally!) shooting it and letting others shoot it, but there were some problems in functionality. For starters the small #10 allen head screws that held the bolt to the bolt carrier would shear in half width-wise after a couple of rounds, and that left me with no way to rotate the bolt lugs out of engagement with the chamber extension. This was a problem, and it was caused by two rookie mistakes.
1. The amount of recoil the rifle has is too much for those small screws to hold everything in place. When fired, the rifle goes from being at a standstill to moving back a good 10 inches or so within the space of a few milliseconds. The inertia of the rifle is carried on to the bolt carrier, and this puts an abnormal amount of stress on those small screws in an attempt to keep everything in one piece.
2. Pressure from blown out primers/punctured primers. The surplus Brazillian ammo we were shooting had incredibly hard primers (seriously, almost-need-a-hammer-and-punch-hard), so we had to reset the hammer and re-strike the firing pin several times for some rounds to go off, and by the time the primer went off, there was usually a hole in the primer. This didn't work too well, because then you have a ton of pressure trying to find the fastest way out of the cartridge, whether from the case neck/mouth or the now-punctured primer. This gas would expand and blow backwards through the bolt, and the first place it would try to escape was.......you guessed it, right where the retaining screws were.
Between the pressure pushing the screws out and the immense recoil, those little screws were shearing with ease. I earned my blog moniker the day of the blogshoot by using some good ol' fashioned redneck engineering to remove the sheared studs from the bolt head (don't ask how I did it, a good tinkerer never reveals his secrets, especially when he knows it was just pure dumb luck), and figured that I needed to attend to that issue so it was not a long standing problem. I built the rifle for fun, because me owning a .50 BMG angers the anti-gunners, (but me building one in my garage probably terrifies them), not for everyday use, so if it needs a little TLC from time to time, it isn't my primary weapon, so I'm not worried about it. However, I would like it to be reliable when placed in other people's hands, and the shearing screw issue was worth the time and trouble to fix.
I didn't take many pictures of what I did because of my lack of a decent camera still, but what I did do was cut some threads on the bolt head,welded a sleeve into the bolt carrier, and then single point threaded the inside of that sleeve to allow the bolt head to thread into the carrier. This way, all the force on the bolt during recoil would be spread out over a 1.5" diameter section of steel, threaded 12 TPI for a full 1.5" length. The bolt threads in quite nicely, locks up in the chamber just fine, and is merely held in position by the same small #10x24 screws. This fixed the recoil issue, but what about the pressure problem?
Easy. I flipped the bolt over and drilled a small hole right in front of the hammer clearance slot. The hole protrudes into the small gap between the bolt head and bolt carrier, and directs any errant gases downward into this slot, where they travel to the rear and exit through the bolt handle slot. It might be a bit uncomfortable to catch wind of these gases in the case of a punctured primer, but it beats shearing or blowing out a screw.
Given that this was my first firearm to build from scratch, and it didn't follow the guidelines of any other rifle out there to the letter, I don't mind admitting that I made mistakes here and there, and then correcting them. As far as the rest of the rifle, I disassembled it in the process of making these changes, and aside from some scratches and small pieces of debris working their way into the chamber and main receiver, there is absolutely no appreciable wear to any of the functional pieces of the rifle. The bolt lugs still lock up well, the headspacing has not changed, there are no overpressure or bulging marks on the bolt face or chamber extension, and the bolt lugs show no sign of being compromised. I'd like to take it all down and have it magnafluxed just to be sure, but with a micrometer and caliper it all still shows to be in spec.
I really wish I had made an extractor and ejector for the rifle as opposed to the shell-holder style of bolt head I made for it, but it seems to be holding up just fine as-is.

Here's the hole drilled forward of the hammer slot...


And the pressure relief ports drilled tangent to the retaining screw holes, as well as the threading on the bolt body.


Next up, we have my new toy.
A while back, my good buddy Six over at The Warrior Class had announced he had a Bushmaster HBAR he was about to take to his local merchant of death and sell. He had owned the rifle for quite some time and had just recently gotten out to shoot it for the first time before finding he really didn't care much for it. I  shot him an email asking for a chance to purchase it, and he responded with an offer I couldn't refuse. So, here is my newest acquisition to my armory, a Bushmaster HBAR with a 20" bull barrel, free-floating forearm, and a pretty decent match trigger. Six is such a nice guy that he even threw in a scope, although I had a varmint scope laying around that I liked a bit more and decided to toss it on there.
If you haven't visited Six's blog, head on over and read. He's a sharp guy with a ton of wit, and is one of those legendary "salt-of-the-earth" kinda people. He's recently lost a loved one, so please go on by and leave your condolences for him and his family.
Six has been a regular reader here for a while, and was kind enough to keep up with me on a personal level last year when I was on a blog hiatus due to relationship troubles. I consider the man (and his family) an extension of my own family, and simply can't say enough good things about the guy.
Here's the Bushy in all it's glory, sitting square on my kitchen table.


On top of all of this other stuff I have going on, I *finally* started machining the magazine blocks for the Hi Point carbine drum solution. I don't have enough progress on it yet to warrant pics, but for those of you who come to my corner of the internet to keep up with the Hi Point drum project, just know it hasn't been forgotten. I've had to really scratch my head about a few aspects of the project, but I think I have the final details nailed, and now it's just a matter of cutting, bending, welding, and machining.

For those of you who have the Suomi itch, I'm doing some parts machining for a guy who is local to me here in the metroplex, and he has given me some great ideas on a couple future projects. One of which is a Suomi/AR/.22 lr hybrid, and another is a Suomi upper for the AR 15. I've been tinkering with the Suomi upper in my CAD system, just to see what would need to be done to make it work. It would be entirely too much trouble to put the magazine well of the receiver tube directly over the AR15 mag well, as it would preclude the ability to use a drum magazine. My solution was just to move the tube mag well and ejection port forward a few inches, placing the drum or magazine about an inch in front of the front take down pin on the AR lower. The rear trunnion on the typical Suomi receiver tube would be replaced by a new section machined of steel that would allow for the take down pin to go through it, and a piece of steel welded to the bottom of the receiver tube would allow for the rear take down pin to be engaged, holding the upper in place just like a normal AR upper.

I am not a fan of having the magazine well of the AR be useless, but in order to use standard, unaltered magazines and drums, this is likely how I would have to go about it. Were I machining one of my 0% AR forgings especially for this project, then I would likely machine the magazine well out of the picture altogether, something like this.
This doesn't show the barrel, barrel shroud, butt stock, grip, etc. but it does go to show that the two designs could work together. I would have to set it up with a reciprocating bolt handle mounted to the bolt, with a slot cut in the side of the upper, as opposed to the rear-mounted, non-reciprocating handle the Suomi normally has, but I still think a 9mm upper for an AR 15 is cool, not to mention that it wouldn't cost a whole lot to build. Toss in the idea of cheap 72 round drums and even cheaper 36 round stick mags, and I think it's worth dropping the 80 dollars on a parts kit in order to build myself one.

I plan to get all the current Suomi parts machined this next week and get them all in the mail, so if you're waiting on a bolt or a threaded rear receiver tube, or a stretched barrel shroud, a striker, firing pin, or whatever you've sent me, start looking in your mail box around the end of next week.
That's all for now, more as I get to it...........

4 comments:

  1. As someone who originally came here for the Hi-Point Suomi conversion, I welcome new news. But I have to say that the ongoing content here is fascinating, and I don't regret the lack of Suomi progress.

    I'd much rather you document having a good time with many projects(and, yes, the AR receiver tap was AWESOME!) than lead us on with a stream of depressive "CRAP: Not There Yet" posts.

    Thanks for your super-human machining and posts thereof,

    Farmkid

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    Replies
    1. Thanks, as always, for stopping by and leaving a comment.

      I'm trying like heck to get that drum conversion to work, I know it can, and I know it will. I just don't always know when. =)

      I'd never call my machining "super-human". More like, "good enough that I'm happy I didn't lose a finger in the process."

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