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Posted: 10/6/2006 1:56:07 PM EDT
| Do the sliding weights in the recoil buffer serve any useful purpose on a semi-auto? I know that they are designed to reduce bolt bounce when going into battery, but it seems like that would only be a concern during full-auto fire where the hammer might fall while the bolt isn't fully engaged and cause a misfire. |
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Yes, they allow the B/C to rearward stall at the end of cycle (the dead blow effect from the weights), which gives the mag more time to recover the top round up to the feed lips before the B/C charges back forward for the strip. Also since we tend nowadays to play dress up with the rife more away from the standards of the normal configurations, the different buffer weights allows us to fine tune the opening of the bolt at cycle, allowing better manipulation of the residual pressures bleed off in the barrel/against the spent case to the chamber wall for a cleaner spent case extraction. |
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I cast a lead plug to fill the buffer and replace all of the steel weights and aluminum spacer. The lead plug is as long as the available space, so it can't slide and the fit is snug anyway. The whole thing weighs about 9.0 oz. or about 4 oz heavier than a standard buffer. My purpose for this was to slow the bolt carrier to ease extraction of loads using heavy bullets with slow burning powders (high port pressures - a poor man's Carrier Weight System). The energy of the bolt carrier should be about the same (slower, but heavier). This should slow down both the backward stroke and the forward stroke since the gas pressure and spring force are unchanged. My concern was whether the lack of sliding weights would be an issue. The slower bolt carrier speed should hopefully make up for the lack of the stall effect you mentioned. I will get a chance to try it soon and it will be interesting to see how it performs and how it feels during recoil. |
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You’re going to get more felt recoil from all of the weight slamming off the back of the receiver extension. If you going to run with the lead plug, look into the MGI softer buffer bumpers (if still offered) to tame down the impact jolt off the back of the tube a bit. |
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Dano, I suppose that is possible, but with the same gas impulse I would think that it would actually reduce felt recoil. If you consider what would happen if you keep adding weight to the buffer, eventually the bolt carrier won't make it all of the way back and there would be no impact against the buffer tube. Between normal bolt operation and one that is too weighted down to function properly, it seems that the bolt carrier impact at the back of the stroke would be continually reduced as opposed to initially increased and then decreased? |
| Actually, the only real felt recoil of the rifle is from the moving mass of the B/C-buffer and not the round being fired. If you pull the weights out of the buffer, this produces the least amount of recoil, but at the same time, you lose all the dead blow effect of the buffer, and when using questionable mags, can have feeding problems. |
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Dano, I don't think that is correct. The bolt is locked until the bullet is within a few inches of the barrel. All of the primary recoil impulse against the bolt is trasfered to the receiver via the locking lugs in the barrel extension. The secondary recoil impulse due to the gas ejected from the barrel also begins before the bolt carrier has moved significantly. There is a third, smaller, recoil impulse when the bolt carrier bottoms out at the rear of the stroke. If the gas system were deactivated so that the bolt carrier didn't cycle, the rifle would still possess most of its felt recoil. |
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You’re over thinking it, With the action as a single shot, the rifle has no recoil. What is felt on the rifle is the movement of the B/C-buffer moving in the rifle (the action), and whole mess crashing against the back of the receiver extension, then again at closer in regards to recoil. If you would like to test, pull the gas tube for a few shots to get a real idea of the lack of recoil a 223 produces, then after that, put the gas tube back in, and run the rifle with no buffer weight in the buffer. Note: on the first ar-15's (full auto's) the buffers were not such, and just a carrier extension to limit the travel of the B/C. The weights where added into the buffer in order to slow the full auto fire rate, and to make the rifle more reliable in regards to allow the mag more time to recover as one of the improvements of the rifle when the plateform became the M-16 series. |
Yes, all the M-16 and AR-15 have some sort of weights in the buffer system to make the buffer work/act as a dead blow hammer at both ends of the stroke. www.biggerhammer.net/ar15/buffers/ |
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