Buffer Weights?

[para1505]

I'm building 6mm ARC, and I will be trying to squeeze all the velocity I can out of it. I did this once with a 6.5 Grendel. I used a adjustable gas block and a Tubb bolt carrier weight and was very successful with it. But Tubb has discontinued the carrier weight. So increasing the weight of the buffer would have the same affect?

 

[_Windrider_]

I'm building 6mm ARC, and I will be trying to squeeze all the velocity I can out of it. I did this once with a 6.5 Grendel. I used a adjustable gas block and a Tubb bolt carrier weight and was very successful with it. But Tubb has discontinued the carrier weight. So increasing the weight of the buffer would have the same affect?

Check out the JP bolt carriers and silent capture spring system. Both use stainless and tungsten weights to change the mass.

 

[para1505]

I've heard that about JP , I've been to their web site before , they have so many options it's kind a over bearing

 

[_Windrider_]

Call them. They will answer.

 

[EM_556]

Buy H1, H2 and H3 and run them. Whichever is the heaviest and works I would use. You could also run a rifle buffer system and stock as well. I really like Geissele’s buffer springs

 

[para1505]

I'll be running rifle spring and A2solid stock

 

[para1505]

Just ordered the tungsten weight set I'll try them 1st and go from there

 

[NukeMMC]

If you're using a rifle buffer for an AR15, there are 5 steel weights and an aluminum spacer inside. On my MK12, I replaced that with 7 Tungsten weights, since I run suppressed 100%. Final weight is 10ozs. Whatever weight you end up using, ensure the rubber shims remain and there's still some "slop" inside as that backlash is part of the effectiveness of the buffer.

 

[NukeMMC]

By the way, 308ARs have 1 less weight and are about 3/8" shorter due to the longer bolt carrier.

 

[para1505]

NukeMMC thanks for the info much appreciated

 

[MALLARD]

No increase in velocity is worth trading reliability. And by your logic if a heavy buffer would work like the tubb cws, then why not just use a heavy spring ? and if thats true why not jam a spacer in the back of the buttstock to compress the spring ? And wouldn't adjusting the gas block to it's most optimum point negate the use of the cws ? Finally, i'd just make a cws myself, if you cant pay someone else to do it.

 

[PJ65C]

I've heard that about JP , I've been to their web site before , they have so many options it's kind a over bearing

I was in the same boat, the manual they have on their site i found to be helpful.

Give them a call - just dont talk with Andre...that guy is down right awful!!!

 

[para1505]

No increase in velocity is worth trading reliability. And by your logic if a heavy buffer would work like the tubb cws, then why not just use a heavy spring ? and if thats true why not jam a spacer in the back of the buttstock to compress the spring ? And wouldn't adjusting the gas block to it's most optimum point negate the use of the cws ? Finally, i'd just make a cws myself, if you cant pay someone else to do it.

Yes I agree reliability and accuracy is what I'm after but trying to find accuracy node in higher velocity

 

[TimK]

Increasing buffer or carrier weight have roughly the same effect. Increasing buffer weight might be slightly better for reliability because that mass actually bounces once when it drives the carrier home adding some hammer effect to bang it closed.

I'm running a JP adjustable mass BCG in a Valk along with their SCS. Be aware that the BCG is heavier than even an M16 BCG even with the steel weights, not the tungsten. I can't recall the exact numbers (I made a chart of all the different weights of BCG's and buffers but it's at home) but if memory serves it's 1 or 2 ounces heavier than an M16 BCG.

 

[nutation]

Tungsten is impressively dense, even denser than depleted uranium. The only things denser are osmium and iridium, which are nearly absent on Earth.

 

[Ripdog28]

There is a lot of guessing in this thread. Be careful. No, the buffer being heavier is not the same as the BCG being heavier. Typing out all the info would be a pain on a phone. People using “hammer effect” are guessing. One slows unlocking/extraction, the other acts like a dead blow. They work together but don’t replace each other in their task.

managing over 60 full auto MK18s, several SR25s and AR10s, and some HKs gives one lots of official training and insight.

look at HeavyBuffers.com and read up. grab a Vltor A5 or RE10 receiver extension then Pick the a buffer recommended by Slash on the site. IMO, the JP variable mass bolt is a great choice. If able to, I would find out the “average” pressure of the cartridge and the dwell time and order a barrel with a custom gas port. Many manufacturers make gas ports too big to increase reliability over the huge ammo spectrum. This causes overgassing which leads to a large variety of potential damage. I don’t believe an adjustable gas block is the answer as I have seen failures with every brand in many guns. (But the gas port was enlarged for reliability) I try to stick with a standard gas block.

I don’t think you will be running 50,000 rounds thru the gun but having guns last over that without major failures other than typical wear parts is nice.

 

[para1505]

I have searched a lot on the web and JP is the only one I can find that makes a heavier carrier. I don't see why Tubb stop producing the carrier wieght. The price that JP has on the variable wieght carrier ($300.00) is hard to sallow for me but I know my rifle would operate a lot better with it

 

[Ripdog28]

If you stick with a standard or full mass carrier, look for a small gas port barrel or, although I hate them, adjustable gas block. Just do regular maintenance on the gas block.or as mentioned above, find a machine shop and have them make you an insert.

 

[LRBuck]

I'm building 6mm ARC, and I will be trying to squeeze all the velocity I can out of it. I did this once with a 6.5 Grendel.

I had to try going lighter in my build (22”, +2 rifle gas). It has a smaller gas port and was under-gassed using Leverevolution for my hand load. Leverevolution seems to be one of the better powders for reaching higher velocities without getting over pressured in this cartridge.

Not disagreeing with the other posts, just sharing my problems that led me in the other direction. Still fine tuning it.

I had no function issues with the factory ammo and a regular carbine buffer/spring, but with the Lever loads I had to get a lighter Sprinco spring and lightened the buffer some too. I don’t shoot suppressed.

None of this may be an issue for your build unless you are going to try Lever and have a +2 gas system on a 22” or shorter barrel. With hindsight, I might have gone with a +1 rifle length gas.

I really like the 6mm ARC despite the function issue I had using Lever. Shooting groups as good a .36 with the Lever hand load (29.6 grains under a 109 Berger LRHT) velocity about 2740. My goal for the build was accurate out to 1200 and on Good Friday, I had 6 hits in a row on the 1200 plate in high wind so I am happy.

Good luck!