Carbine buffer weight experiment

[wideglidejoe]

I'm under house-arrest while recovering from major surgery, so I'm trying to stay occupied without doing anything physically stressing or too heavy. Dr's orders, my wife is the "enforcer". All is OK now, I'm not looking for or needing sympathy, it is what it is, I'll be 100% in a few more days. This recent one is nothing compared to bad motorcycle accident in '04. I can only surf so much on forums, I don't watch much TV, so I'm "piddling around" as my dad used to say. All I ask is the good Lord's favor that I'm up to walking the "worlds largest" gun show, the Wanenmacher's gun show in Tulsa this weekend.

OK, I'm wanting to make one or more "lighter than standard weight carbine buffers". I know you can buy them, that's just not me, and I've got time on my hands. Just for grins & giggles, today I took apart a spare std carbine buffer tube. For this particular buffer tube, the three steel weights & three rubber pads have a total stacked height of 2.045" (all measurements are very quick and dirty for this exercise.) The cavity in the empty buffer tube is 2.660", less the 0.485" portion of the poly plug that goes into the tube, leaving a space of 0.130 for the stack of three spacers and three weights to rattle back and forth in.

My question is, is that 0.130" space needed? Or, is it OK for the spacers & weights to be exactly the same length as the buffer tube cavity and not rattle around?

I'm gonna fine-tune an upper, I thought I'd try the following carbine buffer tubes;

1) 100% empty, no spacers or weights, but tapered poly plug in place.

2) 1 weight, 1 spacer, and a piece of 1/2" wooden dowel rod, trimmed to the length of the 2 missing spacers & 2 missing weights.

3) 2 weights & 2 spacers and a piece of 1/2" wooden dowel rod, trimmed to correct length.

Do I need to make the 1/2" wood plugs the exact length of the spacer(s) & weight(s) I removed, to keep the 0.130" available room to rattle around in, or is it OK for the 1/2" wood plugs, weights & spacers to make a tighter/quieter stack, as long as the poly plug fits and roll pin is in place?

My gut feel is the 0.130" isn't needed, it's the total reciprocating mass weight that matters and makes it all work, whether it's a standard buffer, H2, H3, custom aftermarket, different springs, etc.

I also have a new JP carbine length spring which I'll be trying, which leaves me a stock ~10.5" spring that I can trim a couple of coils from to play with too.

Thanks in advance!
Joe

[Tex Nomex]

You probably don't need that space.
But, if you own a dead blow hammer, you know there's a little space in it.
I've always thought the dead blow aspect may work to alleviate bolt bounce.

I customize mine by putting a small spring inside the buffer at the very end next to the nylon endcap. Buffer doesn't rattle when walking around or on the rearward stroke, but still dead blows when it hits the bolt carrier. Seems to work just fine. Just an experiment I stuck with... YMMV

[grayfox]

There are a couple of after-market buffers that advertise they don't have that slip-slop space so I'd imagine you don't need it. The recoil spring has the energy absorption/distribution function, using recoil spreads out the reaction impulse at the shot over time to smooth out operation and provides the force to (with gas) extract and (spring, buffer and bcg) load the next round... Also, don't think there's anything in there that needs any hot-cold expansion room. So you could certainly take it up with the dowel rod a bit longer than the wts you are replacing.

[98Z]

I've always thought the dead blow aspect may work to alleviate bolt bounce.

That's exactly why it's there.

[rickt300]

I have intentionally used rifle buffers with both my AR Grendels, and thought this would be better overall. Why go lighter?

[wideglidejoe]

I have intentionally used rifle buffers with both my AR Grendels, and thought this would be better overall. Why go lighter?

It's a 12.5" 6.5 Gr pistol. I feel the barrel port is too small, it has all indications of being undergassed. I'm thinking of trying lighter spring &/or buffer instead of drilling the gas port bigger. I won't spent a lot of $$'s on my buffer experiment, just time, and if that don't work, I'll either drill the gas port larger myself or send the complete upper back to the vendor to test it and enlarge the gas port if they deem it necessary. If I decide to drill it myself, which I'm capable of doing, I just "bought" the problem if it's something else. If I send it to the vendor, I'm out the time of a round trip. I'm not bashing the vendor, they have great customer service, and they've already offered to take it for troubleshooting, if I choose to send it back. Bottom line, I guess, I'm trying to prove to myself it's undergassed. If lighter spring &/or buffer works, I may send it back anyway. I have multiple lowers that were originally built as pistols, now configured as rifles/carbines, but this particular lower is set up the way I want it, and will stay a pistol, sharing a 10.5" 5.56 upper and this 12.5" 6.5 Gr upper. By the way, the 5.56 upper has run fine with several hundred rounds put thru it on this lower, with a standard carbine buffer & spring, so it's not the lower.

I do have a Grendel 18" rifle, it uses rifle buffer and spring with a M16A1 fixed stock.

Thanks,
Joe

[Greyling]

I had a blackout that was giving me issues with my light loads, so I cut 3 coils off the recoil spring. Problem solved. I also tried lightening my buffer. It helped some, but the lighter spring did more.

[98Z]

Joe, my 12.5 runs great, standard carbine buffer, Armalite AR15 carbine spring, KAK Shockwave pistol receiver extension. My difference wasn't going lighter, though, but going heavier - I'm running the LAW Tact folding stock adapter, in which you stick a steel extension in the back of the BCG to lengthen it, in order to work with the folding adapter. That extension weighs exactly 62 grams, or 2.187 oz. I'm effectively using a 5.2 oz carbine buffer. Faxon 12.5" Match Grendel barrel.

Might be worth trying something heavier, as well as lighter.

[wideglidejoe]

Again, Thanks for all the comments and suggestions. I hope to get to the range soon, as soon as I get released from the doc (maybe Fri?), and feel a little better. Every time I go to the range, I'm taking lots of stuff with me, a storage tote of "stuff", full ammo cans, etc. I'm on a lifting restriction right now.

Man, it's supposed to be near 80 F here today, high winds (20+ mph), but supposed to be back in the 40's for highs, and lower 30's for lows this weekend. Gotta love OK weather!

Greyling, which did you try first? Shorter spring or lighter buffer?

98Z, I too am running the LAW folder on this pistol. With a 10.5" 5.56 upper, it runs perfectly with stock carbine buffer and spring. Since I've used a dial caliper on the gas port on my 12" 6.5 Gr barrel at 0.0550, and I've been told it should be 0.0595 from factory, and others have said they've opened theirs of the same brand to the upper 0.060's", I'm just thinking I'm undergassed. When I get back to the range, I'm taking a new JP carbine spring, the existing stock carbine buffer & spring, an H buffer from another carbine lower, another standard buffer that has had one weight removed and replaced with a spacer, and another carbine spring that may be shortened a couple of coils. I'll take my time and play with it, see what happens, and get back to y'all.

[Greyling]

I tried the buffer, then the spring, because the buffer mod was reversible.

[wideglidejoe]

I tried the buffer, then the spring, because the buffer mod was reversible.

Thanks!!

[98Z]

Again, Thanks for all the comments and suggestions. I hope to get to the range soon, as soon as I get released from the doc (maybe Fri?), and feel a little better. Every time I go to the range, I'm taking lots of stuff with me, a storage tote of "stuff", full ammo cans, etc. I'm on a lifting restriction right now.

Man, it's supposed to be near 80 F here today, high winds (20+ mph), but supposed to be back in the 40's for highs, and lower 30's for lows this weekend. Gotta love OK weather!

Greyling, which did you try first? Shorter spring or lighter buffer?

98Z, I too am running the LAW folder on this pistol. With a 10.5" 5.56 upper, it runs perfectly with stock carbine buffer and spring. Since I've used a dial caliper on the gas port on my 12" 6.5 Gr barrel at 0.0550, and I've been told it should be 0.0595 from factory, and others have said they've opened theirs of the same brand to the upper 0.060's", I'm just thinking I'm undergassed. When I get back to the range, I'm taking a new JP carbine spring, the existing stock carbine buffer & spring, an H buffer from another carbine lower, another standard buffer that has had one weight removed and replaced with a spacer, and another carbine spring that may be shortened a couple of coils. I'll take my time and play with it, see what happens, and get back to y'all.

I'm pretty sure I'm almost 0.070" on the port diameter on the Faxon 12.5" carbine gas barrel of mine. Might be slightly under by a thou or two.

[Lastrites]

If you decide to cut coils make sure to check that the key on the bcg doesn't impact the receiver on it's rearward travel.

[wideglidejoe]

If you decide to cut coils make sure to check that the key on the bcg doesn't impact the receiver on it's rearward travel.

Will do!

[Troutguide]

I lightened my buffer and added a piece of heavy silicone tubing to take up the slack seems to work well so far. I think you will be fine but why not just leave the tiny gap since you need to measure your cut anyway. I have a low mass bcg, jp light carbine spring and a super light buffer(about like you say 1/3 the weight) I had to cut my single weight to adjust. Adjustable gb tuned almost closed then opened just enough to cycle wolf steel consistently. Light with little recoil. Very nice in my opinion.

[wideglidejoe]

I lightened my buffer and added a piece of heavy silicone tubing to take up the slack seems to work well so far. I think you will be fine but why not just leave the tiny gap since you need to measure your cut anyway. I have a low mass bcg, jp light carbine spring and a super light buffer(about like you say 1/3 the weight) I had to cut my single weight to adjust. Adjustable gb tuned almost closed then opened just enough to cycle wolf steel consistently. Light with little recoil. Very nice in my opinion.

Thank you for sharing your experience, I'll keep it in mind too!

Thanks to everyone who has replied to this thread! I'm looking forward to the next range trip and try to find the right combo that works.

I appreciate this forum, lots of knowledge and expertise that's willingly shared, and considerably more laid back than some other forums I hang out at for guns, cars and Harley's.