Have heavy buffers fully mitigated issues associated with carbine gas systems?

[crazymoose]

Title pretty much asks it all, but I'm especially wondering in regard to 16" barrels with carbine gas systems.

As I understand it, the bolt/cam pin lifespan issues associated with carbine gas systems, especially on 16" barrels, were a function of the greater carrier speed placing more stress on the bolt lugs and cam pin as the carrier traveled rearward during unlocking. However, when H2, H3, and 9mm buffers are used, the reciprocating mass is increased, and the carrier and buffer should theoretically travel more slowly, thereby putting less stress on the bolt lugs and cam pin.

Am I overlooking something, or should one expect much greater bolt lifespan when using heavy buffers than with the standard CAR buffer/gas system setup?

[gunner76]

I was told that when you increase weight behind the bolt either with a heavier carrier and or heavier buffer, it increases the dwell time before the bolt starts to unlock, so the pressure is less, thus causing less wear on the lugs.

[Robb Jensen]

An H or heavier buffers aren't really a fix but more of a bandaid. The gas pressure is still high and they suffer from gas port erosion more than barrels with longer lower pressure gas systems.

A longer system is the real fix. Midlength gas systems for 16"-18" barrels is really the way to go. Intermediate is even better for 18" but few companies make them. Rifle gas for competition (3gun) 18"s and rifle gas obviously for 20-24" barrels.

[sinister]

That carrier is still reciprocating and the bolt cam pin is turning in the carrier raceway faster than on a 20-inch rifle.

If the cam pin isn't hard enough it'll gall. Incorrectly hardened and shot-peened bolts are going to crack in the same places.

Armalite has done some engineering to take stress off a couple of bolt locking lugs.

The price of doing business with a 7.0 or 9.0 gas system (even with heavier buffers and carrier weights) is higher port pressure and bolt group velocity.

[Boss Hogg]

The buffer spring is also part of the equation. I've learned a lot from Mike Pannone on this topic and you may want to check out Sprinco's offering.

the last time I bought a carbine-length gas system was a S&W 5.45 AR upper.

http://sprinco.com/tactical.html