Zamex/blckwlfny,
Zamex has photographic-skills....he could post clear-close photos of the bolt-face, and inside the top-cover....maybe the inside of the chamber or at least the barrel-markings. Something is causing the scratches on the Blanks, and the inability to chamber/fire from the belt.
Again, with his clear photos of the plastic-blanks.....they show uniform scratches around the case just below the "neck" area............what do you think caused them (?)...........not the belt..........and if it was a rough chamber-entrance the scratches would be more to one side/area as the chamber entrance is of a larger diameter.
If the pressure-plate in the top-cover was not of the correct angle, might make the chamber-direction at an incorrect angle. There are several other things we need more information on at this point.......as this is an old-post, did he correct everything by this time....is it still giving him challanges (?).
Clear photos and a good discriptions of the challanges from the beginning will help......(I believe that his gun is an MG42/M53-version, and not an SA42) ....did the gun fire live ammo in 8x57mm before he Blank-Adapted it.....what did he use to Blank-Adapt his gun (?).......and at this point, clear photos of the "jams" as they are in the gun helps, but we need more information and/or photos to help him.
To be clear.....is this an 8x57mm chambered-barrel-assembly or 7.62x51mm/.308 barrel-assembly (?)...or is there a separated case-front inside the chamber (?)....or rough-chamber-front (?).........More than likely, this may be cause those scratches on the plastic blanks if he doesn't have the correct barrel-assembly.
The cuts on the case-rims look more like a cut from a broken-extractor....and why I requested a photo of the bolt-face.
Regards, RichardS in MI.
US Army, Retired
Blanksguy2001@charter.net