[headquarters]

It is piston driven ,but other than that relatively similar to the M4 .

I have to say ,it is a h**l of a gun.Even if it is only .556 and not our trusted
.308

Its piston system is very rugged and so far it has taken the abuse I have been allowed to dole out .

Some say that it cant take cold -this is false. It is used regularily at temperatures as low as -25C* up here -and it functions well.

As for gunk build up in the piston system -yes there will be a moderate fouling . But I think over 1000 rounds or more can be fired without even field stripping the thing .( For various reasons thats how many got through mine before a total cleaning .It wasnt badly fouled and could have taken alot more.)

Now,all AKor AR people out there this is just a preferance on my part -and it is alittle bit of both models this HK 416..