[Perplexed]

I've noticed that some RPK's (AES-10B in this case) have smooth receiver top covers, while others have three ridges running across the cover. What's the significance of these ridges, and are they something to be desired or avoided? TIA!

 

[DudleyDR]

From what I have read, the design of those stamped/pressed ridges plus the three "mini-ribs" on the top (all used to stiffen the sheet metal from flexing) appeared at about the same time as the stamped-and-folded sheet metal receivers, which would not have the same rigidity as a machined receiver.

Raised ridges are common in magazines and are there for stiffening/anti-flex purposes. Raised ridges, folds, and crimps can allow the use of a lighter gage sheet metal to achieve the same strength as a thicker, flat sheet.

Those protrusions have a structural function and I have seen them on various models. When assembled, those top covers add some rigidity to the firearm unit. They are pretty well "fixed" front and rear and the overlapping "lips" on the sides also help. DDR

 

[Guest]

Some later RPK's have the ribs stamped in them others have the more traditional milled style smooth cover .The romanians used both .I had a 1964 RPK with the stamped (ribbed cover) that was stamped matching .Had to have been done at a latter date ,but heck it was stamped matching . And an aes10b with a milled smooth style and seen others with the ribbed stamped style . So either is correct. The smooth cover is heavyer grade sheet metal .The ribbed is lighter sheet metal .but the ribs add strength to the lighter grade sheet metal .So they come out equal in strength. The romanians are just using what they have laying about it seems .