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Posted: 6/8/2014 8:18:05 AM EDT
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I finally got my Project Guns receiver and semi parts kit. Yesterday I machined my lower, installed the semi parts, did all the fitting required to get that working, then machined the bolt carrier to fit the receiver, removed the firing pin striker, machined the sear pocket out, drilled and reamed for the floating firing pin extension, fit that to the receiver and test assembled. Then I turned the barrel down, indexed it and pressed it in all the way to the shoulder in the receiver.
All seemed to be going fairly well, it was a lot of work to do in one day, and now I have issues I'm hoping other builders have insights on or have encountered themselves, because up to this point I've simply relied on my machining experience and general firearms knowledge and I have zero RPD experience other than this. 1. It will absolutely not headspace the way it's currently configured. I have not yet drilled and pinned the barrel in place. If this were an AK, I would push the barrel back out until it headspaced and pin it there. Is this an acceptable method with the RPD? I know the project guns video says to trim the locking lugs, which I'm capable of doing, however it's not a matter of 0.005 or 0.010" it's closer to 0.060"+ of interference. Bolt bottomed out on barrel tenon with no case or gage. Cam follower should be all the way forward? 
2. The project guns semi auto parts consist of the fire control stuff, which I have working properly, and a striker block which relies on a spring that impinges on the recoil spring guide. When trimmed to the recommended length (in PG's video) it has enough force to over come the recoil spring, and keeps the spring guide from coming all the way forward with the carrier. Are newer, stronger recoil springs required? Where do I find one, or should I just try to find one myself at McMaster or something? 3. What the hell is this thing, what does it do, where does it go? 
4. Headspacing issue 2. This is how much of a regular case sticks out from the chamber. I've chambered and headspaced a few guns, handguns and rifles, and I've never allowed this much projection from the chamber. Does this seem right? This is a Military Gun Supply purchased Polish kit that included a Polish barrel (not a demill). 
Bolt on the round 
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Make sure your round is getting completely chambered. I ground the flappers on mine for headspacing. You have to keep a slight angle on them so they maintain total contact with the receiver. Play with them in the receiver ahead of time and you'll see what I mean. It would be easier for you to headspace by pushing the barrel out though.
That mystery part you have is the f/a disconnector. You won't need it. |
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Forgot to update this.
I found the problem. If I had assembled the barrel to receiver at home this wouldn't have been an issue. But I did it at work, in our nice new Dake 50 ton press instead of my rickety old cheap Harbor Freight 12 ton. There is a false shoulder in the receiver, about 0.010" step. I pushed the barrel in right past that. It was squeezing the chamber as well as the barrel being too far in. I pushed it back out and pressed in to the correct headspace with the flaps and am happy with the engagement without any trimming. I have it hand cycling rounds now and am waiting on a few parts I ordered from Wise Lite that weren't in my parts kit (namely the gas regulator and the handguards). |
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Quoted:
Very nice. Hopefully I will find the time to get mine built. I have all the parts but not the time. I managed to squeak out a full day in the shop without my wife or someone else begging my time, and got all of the semi conversion machining done in a day. If I hadn't I'm sure I'd still have a box full of parts 
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