Build Thread H1 or H2 AR Buffer to Fix Over-gas?

[RaceFan]

For the Brain Trust, the following question to adjust my over-gassed rifle build.

Salient rifle information:

• 18-inch barrel
• non-adjustable gas block
  
• Magpul UBR stock
  
• standard buffer spring
• currently running a carbine buffer

The casings are ejecting at 2 o'clock; ideal would be 4 to 5 o'clock, which is what I'm trying to achieve by slowing down the BCG.

Should I use an H1 (3.8 oz) or H2 (4.8 oz) buffer to address? Wanted to see if others cured without trial and error on my part. I guess I might even have to go H3 (5.4 oz)...

Thanks!

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[jordanka16]

Before anything else I would try an adjustsble block, they are really nice. Second, you'll have to get one of each to see which one you like most. I usually do the H2, seems to work pretty good in most anything. Buy one of each for a range testing kit.

2 o clock is only a little overgassed, 4 is about perfect, I bet the H1 would work.

 

[RaceFan]

Before anything else I would try an adjustsble block, they are really nice. Second, you'll have to get one of each to see which one you like most. I usually do the H2, seems to work pretty good in most anything. Buy one of each for a range testing kit.

2 o clock is only a little overgassed, 4 is about perfect, I bet the H1 would work.

Thank you!

I'm shopping now. Yup, figured I'd get both H1 and H2 and test at the range. I'll post results once addressed.

 

[titsonritz]

You should be using the heaviest buffer that will reliably lock back on the last round. If you are truly over gassed I would think you'd want an H2, and H should be the standard and the standard carbine buffer should be thrown in the ocean.

 

[Member 3687]

You should be using the heaviest buffer that will reliably lock back on the last round. If you are truly over gassed I would think you'd want an H2, and H should be the standard and the standard carbine buffer should be thrown in the ocean.

I would have to agree with titsonritz you run the heaviest you can to be reliable. In most of my builds I run H2s and my pistols I run H3s. Even my 2 factory colt M4s came with H2 buffers. Yes they will run on STD buffers but the recoil is felt a lot more and follow up shots are not as fast because of it.

It seems most aftermarket barrels drill their gas hole a bit large so they can run light load .223 as well as heavy load 5.56 without requiring an adjustable gas block. Since most folks do not shoot all that much they do not realize the beating their gun gets over time by doing this.

If you are going to run the same bullet weight and manufacture 80% of the time you can tune your buffer weight to match and be good to go. But if you run from light load 40gr .223 to heavy 77gr 5.56 then an adjustable gas block may make since but personally I have never found a need for one.

Good luck

 

[titsonritz]

It seems most aftermarket barrels drill their gas hole a bit large so they can run light load .223 as well as heavy load 5.56 without requiring an adjustable gas block.

That's exactly what they are doing and why their barrels are so "blasty" and why I'm so finicky about which barrels/uppers I buy.

 

[sed]

If you're open to tinkering, you can purchase an H3 and make your own H1 and H2 by using your Carbine buffer.
Standard buffers (not the Spike's - they use Tungsten powder) have three weights separated by rubber washers.
- Carbine has three steel weights and no tungsten weights.
- H or H1 has one tungsten and two steel.
- H2 has two tungsten and one steel.
- H3 has three tungsten and no steel.

You can run/test the H3 and if it's too much, you know you need an H or H2.
Using your carbine and H3, you can open them up and reconfigure the weights as desired to make your own H and H2 to try out.
To open the buffer up, you drive out the roll pin that holds the rubber/plastic bumper and then remove the rubber/plastic tip. As a caution, these rubber/plastic tips can be very difficult to remove sometimes. With the rubber/plastic tip out, the weights will come out.
With weights out, you can reconfigure to make an H1 and H2.

If this is more tinkering than you want to deal with, you could:
- Borrow a buddies H, H2 or H3 for testing; see which one runs the best, then purchase said buffer or
- Purchase a couple different buffer's for testing and final use and know you'll have a spare for a future build or testing

Good luck!

 

[Member 3687]

I have complete uppers from BCM in 11, 14, 16 and 20in Colt in 16in and PSA 7, 10.5, 16, and 18in and have built from the ground up using BCM, Faxon and a few no name generic barrels and yes there are major differences in barrel quality and in gas hole size between the manufactures in the same barrel length.

I have also found that not all buffer springs are the same even if sold as mil spec. The spring can play a big part in the operation of the system as well as the buffer weight.

So I end up getting my carbine springs and buffers from BCM as they have been consistent in tension from lot-to-lot and I know what to expect.

I feel if you find something that works you stick with it till you find something better.

I build these things like puzzles and have way too many but I enjoy a challenge to make something run better than they should. I have even wasted a few barrels getting un-drilled ones then trying different sizes holes until they become a danger by providing two much gas pressure just to see what happens. It was fun but I did not have any true way to measure my outcome other than felt recoil and part wear.

So over time I found that just buying drilled barrels and playing with the buffer and spring till it works for the verity of ammo I use is easier than playing with an adjustable gas system all day because most folks just find a happy medium setting then leave it there anywhere.

 

[titsonritz]

I have also found that not all buffer springs are the same even if sold as mil spec. The spring can play a big part in the operation of the system as well as the buffer weight.

So I end up getting my carbine springs and buffers from BCM as they have been consistent in tension from lot-to-lot and I know what to expect.

I use Sprinco springs, blue for carbine, green for rifle and A5 with Vltor buffers for the A5 system, which is all use on my new builds.

 

[RaceFan]

Went to the range yesterday after changing to an H2 buffer. Worked like a charm. Fixed.

 

[edzz]

Went to the range yesterday after changing to an H2 buffer. Worked like a charm. Fixed.

Not acceptable.
Your not putting enough time and money into this problem. Changing a buffer is only a one minute project.

You really need to change to an adjustable gas block as this will allow you to spend more time and money attempting to fix this issue, and possibly damage your rifle in the process of removing and replacing your muzzle device and gas block.

Honestly, taking the easy way out just because it solves your problem.

Now back to the real world.
Glad you found a simple solution and thanks for letting us know what worked for you.

 

[P7M13]

If you're open to tinkering, you can purchase an H3 and make your own H1 and H2 by using your Carbine buffer.
Standard buffers (not the Spike's - they use Tungsten powder) have three weights separated by rubber washers.
- Carbine has three steel weights and no tungsten weights.
- H or H1 has one tungsten and two steel.
- H2 has two tungsten and one steel.
- H3 has three tungsten and no steel.

You can run/test the H3 and if it's too much, you know you need an H or H2.
Using your carbine and H3, you can open them up and reconfigure the weights as desired to make your own H and H2 to try out.
To open the buffer up, you drive out the roll pin that holds the rubber/plastic bumper and then remove the rubber/plastic tip. As a caution, these rubber/plastic tips can be very difficult to remove sometimes. With the rubber/plastic tip out, the weights will come out.
With weights out, you can reconfigure to make an H1 and H2.

If this is more tinkering than you want to deal with, you could:
- Borrow a buddies H, H2 or H3 for testing; see which one runs the best, then purchase said buffer or
- Purchase a couple different buffer's for testing and final use and know you'll have a spare for a future build or testing

Good luck!

Damn good info there, do we have a AR15 build wisdom sticky? That should be included....
Glad you got it fixed so simply. I would have suggested, push out the roll pin, add or subtract weights.
Not all buffer manufacturers have the rubber washers. Those are the ones that sound like pepper mills when you shake 'em.