Not being a CAR-15 owner,I don't know the difference between the H and H2 buffer, but if one weighs more than the other, get that one. Good things come from a heavier bolt or buffer. Less perceived recoil. Softer chambering of rounds. IMHO in general, less pounding of the infrastructure. They say it slows the entire cycling action, but I could not detect a difference in time. I suppose we don't do well detecting percentages of a milisecond.
I'm running 4 ounces of additional weight in my bolt, which is similar to a heavier buffer and I really noticed a change in the recoil impulse when I added it. Also, I swear my groups tightened up a little. Here's a 5-shot string at 100 yards from today. 225 gr FTX 35gr Lil Gun using the resizing die as a taper crimp die. That's 2.15" OAL not 2.015
Hoot