Total Dynamics of AR Buffer?

[bamashooter]

I understand the heavier the buffer the slower the rearward motion of the cycle. I find nothing regarding how a light buffer vs heavier buffers impacts the forward cycle motion and ultimately the impact of the bolt to barrel extension. Is there a trade-off? Slower rearward cycling sacrificed by a hard slam, outrunning a magazine spring, etc? I try to apply Newton's Third Law here but ........... Never claimed to be a boy genius.

Yesterday, I used the same newish buffer spring (basic JP), however, I switched from a carbine buffer, to an H buffer, ending with an H3 buffer. This was in a new 8.5" barrel pistol (5.56). The pistol came with the carbine buffer (unmarked and weight). Each test consisted of 2 rounds of basic 55gr FMJ box ammo. The bolt locked back with each buffer. Really didn't notice a difference in felt recoil, muzzle flip, all that stuff. The brass all landed approximately 4-6 ft away in an area perhaps of a 4ft or less diameter. Brass ejected from approx the 2:50 position to about 3:10/15 position. The only difference with the brass was that the H3 buffer did a harder, more direct launch of the brass though it landed in the same "group" area of brass.

Thanks

[Clint]

Well...Its complicated...

The gas system delivers an impulse which translates into a momentum of the reciprocating mass. p=mv

Depending on the mass, this translates into more or less kinetic energy. KE = 1/2 mv^2

The spring essentially operates on energy, taking a certain amount of energy to compress.

Whatever leftover energy the buffer has once it fully compresses the spring, is involved with a lossy elastic collision with the end of the receiver extension.

The moveable weights in the buffer may be involved with this.

That lossy collision results in some initial forward velocity, which is increased by the spring releasing it's energy.

When the moving assembly gets up to full speed, it crashes into the barrel extension and undergoes yet another lossy, semi elastic collision.


Bottom line, a lighter buffer results in higher velocities and energies than a heaver buffer.

[bamashooter]

"Well...Its complicated...". You're telling me.

That's what I thought. Not really. Had no idea. Therefore perhaps that "Third Law" applies.

Light weight buffer = maximum cycle speed in both directions.

Proportionally, increased buffer weights retard the speed in both directions.

That's pretty much what I thought however I wasn't certain.

It sounds like with conventional buffers using loose weights, the "inertia" of those weights acts similarly to a dead-blow hammer.

Thanks.

[MistWolf]

Colt has found that the H buffer has less carrier bounced than the carbine buffer in semi auto fire. That's why Colt uses H buffers in their semi auto carbines. They also found that in full auto ARs, the H2 buffer has less bolt bounce than H buffers. That's why their auto carbines use H2 buffers instead of H buffers.

[bamashooter]

Thanks. I was watching a slo-mo bounce video yesterday which I believe included 3 buffers. I walked away believing they each bounced now and then some bounces more sever than others, but it was very inconsistent.

[triggerjerk]

Discussion of this topic still wierds me out. Have a carbine gasser w adj block I liked best tuned to std spring/h buffer. Have a mid gasser adj block that I like best with blue spring/h2. Shared lower that I swap parts out on. Had wanted to run same combo w either upper. And on middie, same 5 clicks to run stouter ammo w h2, extra click open to run Wolf G. With h, same 5 clicks to run stout ammo but it would run Wolf on same setting. Go figure.