BUFFER WEIGHTS
Rifle - 5.15oz, made of aluminum
CAR - 2.9oz, made of aluminum
H - 3.77oz
H2 - 4.7oz
H3 – 5.6oz
9mm - 5.47oz, made of steel
Special purpose buffers designed for suppressed SMG's or 9mm carbines using high pressure (+P+) ammunition
9mm A - 6.3oz CAR style buffer
9mm B - 7.1oz CAR style buffer
9mm X - 7.9oz CAR style buffer
IMHO... If I had a carbine, with a carbine length gas system, and wanted to use a telestock, I would START with the 5+ ounce 9mm buffer. If that setup was reliable, i would STAY with it. I might even start with the X buffer.
Chen Lee (SMGLee), did an EXCELLENT thread a while ago about: carriers (enhanced, regular, m16), buffer weights (H, Regular, 9mm), and gas tubes (carbine, fat boy), and different combinations there-of. His posts were well written and VERY informative.
The gas pressure at the gas port of a carbine length gas tube system is around 26,000 psi. The pressure of a rifle length is around 13,000 psi. The AR is a system, and a system needs to be in balance to work reliably and not tear itself apart. If you are increasing the pressure acting on the system, you need to INCREASE the countering force (the weight of the parts this force acts upon).
You can increase the weight so much so that the system becomes unreliable… short stroking, and unreliable with certain types of under-powered ammo. So you want a certain amount of “over-power” so it remains reliable with all ammo and under all conditions.
FWIW, when I finally get the $ for a Magpul stock for my 20”, (rifle length gas system mind you), I am starting with the 9mm buffer. If the weapon functions with all ammo, then I am not changing a thing.
Have a good one.
Stainless