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Old 12-12-2012, 5:41 AM
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6mmintl 6mmintl is offline
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Nicoroshi sent me a PM with pics of screw build failure, two of four button head screws popped off and upper receiver holes elongated, holes elongated as he stated “Due to weak recoil spring battering rear trunion”.

I PM/answered below, his pics disappeared from my CG inbox message? why?


Nicoroshi, Interesting but have a few questions.

Rear trunion does not look to be original, assume its cast steel? are originals forged/machined billet from various country's?

Can you see battering on parts kits original rear trunnions indicating weak recoil springs prior to rebuild?

Dont see any discussion on replacing recoil springs "Just in case".

Another rivet/pin/recoil lug seems in order if this is a potential design error.

Why no "Flat Head Screw" builds? definitly more surface contact area in shear with countersink into trunion but is there enough "Meat" (wall thickness") in the rear trunion?

Failure mode seems to be a design/parts failure and not a fastener issue, I dont see a rivet holding up for long in this scenario either.

Expecting these gun builds to digest various surplus ammo let alone hotter handloads seems to be a potential receiver failure waiting to happen.

I still cannot believe local builders can rivet as good/strong/secure/proper rivet mtl. as the original factory process.


Maybe a Rivet failure mode sticky is in order?

Im tempted to build an RPK with a .308 dim. barrel and adjustable gas block to see what these beasts can do accuracy wise with good bullets and handloads at distance.