I am bout half done with a 4 cut weld up M53 build. Everything measures in spec from all the drawings i have found, camming piece fits perfectly, top cover fits perfectly, so far so good..... until i put the rails in and the bolt had to be hammered in to fit.
not good. A little filing, massaging here and there and now I can push it about half of the way forward before it stops and binds. The rails are just held in loosely with a couple temporary screws.
I am using new rails that seem to measure the same as the old ones except for being .010" wider so I filed them a bit to match.
Im kind of at a loss.... (and i have a lot of experience doing stuff like this, and a lot of gun builds under my belt)
Could I just have a slightly wider bolt? The receiver seems to measure but i cannot find all the measurements I want. (width, inside with of installed rails, bolt dimensions)
If I open the receiver any wider, my top cover isnt going to fit.
Mu next option is to flatten out the rivet dimples just a bit but i really wanna know what's going on. The internals are not matching numbers to the receiver.