Let's put it this way; since the first day we received the new SRC RPK, which has the same internals as the AK47, we've fired a little more than 100,000 rounds at full auto, and after the first internal inspection the piston barely showed any visible wear. Keep in mind that these guns are shooting between 350 and 375 fps, so we are not talking about a weak spring. Since 100,000 rounds wasn't enough to break the piston we put everything back together and fired some more box magazines through it, and we are happy to say that the RPK is still in fantastic working order and is sitting on display in our walk-in store. 100,000 rounds of constant firing at over 350fps is harsh treatment for a gearbox and its internal parts to undertake