Buffers and Springs

[Shawn Dodson]

Buffers and springs are bandaids and snake oil.

BINGO! But they are easy to replace and have some effect hence their popularity.

Adjustable gas blocks are an unnecessary failure point at one of the most critical points of keeping it a semi-automatic rifle.

Once an adjustable gas block is set you don't fuck with it (unless you swap back and forth between shooting with or without a suppressor).

The gas port on the (non-adjustable) MicroMOA Baby Govnah gas block ($30) can be easily drilled to whatever diameter works best on a rifle but it takes a little time and effort. It requires a cordless hand drill, a set of bits, and a little trial and error and can be accomplished on the shooting bench at the range.

If you want it to shoot flatter, screw on a comp/brake.

I haven't found one that really works.

[M2CattleCo]

Buffers and springs are bandaids and snake oil. Adjustable gas blocks are an unnecessary failure point at one of the most critical points of keeping it a semi-automatic rifle. If it runs, leave it alone. If you want it to shoot flatter, screw on a comp/brake. If you want to change components, buy a barrel with a correctly-sized gas port.

This.

Springs that can rust won't be in my carbine. I use Colt springs and H2 buffers in my three 16" Colts.

[MistWolf]

I find the utility of the adjustable gas block outweighs it's minor potential as a failure point. Getting a barrel with the correct gas port diameter is the right way to do it but doing so is often easier said than done.

An AR requires a certain amount of momentum developed within a minimum and maximum carrier speed. That means the mass needed is pretty well fixed. It's best to start with that mass then adjust gas flow (either by using the right diameter gas port or an adjustable gas block with a slightly oversized gas port) and spring rate to get the right speed

[KeeFus]

Necropost

I’m relatively new to working on ARs. I bought a used carbine M&P 15 which shoots fine and is very accurate. I noticed last week that it was throwing the brass between 1 and 2 o’clock. I cleaned it well and noticed that the gas rings were very loose so I checked them as I was shown in the Army by standing the bolt and carrier up on the bolt...it collapsed. I replaced the gas rings and while replacing things replaced the extractor spring, silicon insert, and o-ring (all those were bought from BCM).

Today I shot it again and it still deposits the brass between 1 & 2 o’clock. Looking at the buffer, the face seems beat to hell. I ordered a new “H” buffer (currently has a carbine buffer) and spring from BCM today. Otherwise this gun runs well. No other problems. Depending on which video you watch or publication you read you may or may not have a problem.

Am I overthinking this?

[MistWolf]

Don't worry about ejection pattern. How the recoil feels is much more informative. If the buffer hits hard against the back of the RE, recoil will feel sharp. It's a sign the carrier is moving too fast. You're on the right track by installing new springs and an H buffer. If recoil is still sharp, check the gas port diameter.

[MSparks909]

Necropost

I’m relatively new to working on ARs. I bought a used carbine M&P 15 which shoots fine and is very accurate. I noticed last week that it was throwing the brass between 1 and 2 o’clock. I cleaned it well and noticed that the gas rings were very loose so I checked them as I was shown in the Army by standing the bolt and carrier up on the bolt...it collapsed. I replaced the gas rings and while replacing things replaced the extractor spring, silicon insert, and o-ring (all those were bought from BCM).

Today I shot it again and it still deposits the brass between 1 & 2 o’clock. Looking at the buffer, the face seems beat to hell. I ordered a new “H” buffer (currently has a carbine buffer) and spring from BCM today. Otherwise this gun runs well. No other problems. Depending on which video you watch or publication you read you may or may not have a problem.

Am I overthinking this?

I’m usually a fan of H2 buffers in 16” carbine gasser ARs but the H should work fine.

[Unobtanium]

I find regular carbine and rifle mil-spec springs unreliable in actual practice, and prefer the Sprinco Blue (carbine), or Sprinco Green (for A5/Rifle), and then I find the heaviest buffer that will run PMC .223 on a clean, well-lubed gun, just BARELY, and then back off 1 buffer weight.

[entropy]

Here’s something that might help. A while back I was trying to tune a pistol upper and found it helpful.

https://i.pinimg.com/originals/7e/ce...531edabdba.jpg

Attachment 24718

[MistWolf]

The ejection chart is a poor indicator of gas drive. There are too many variables involved, such as extractor and ejector spring strength, both of which will change the ejection pattern. The right way to tune an AR is by using the lock back check and how the recoil feels. I'll have to double check, but when I was tuning the upper with the adjustable gas block, I don't think I ever got an ejection pattern further back than 4 o'clock, even when it was undergassed. By undergassed, I mean the rifle would eject but not lock back. Closing the gas another click from there resulted in to extraction at all. The set up was carbine RE and tested with carbine, H and H2 buffers with a Colt factory action spring. The result was the same when testing an A5 RE annd A5H2 buffer and Sprinco green spring.

Using a heavier buffer to fix an over gassed AR is useless if the gas flow isn't corrected by using the right gas port diameter or an adjustable gas block.

[Leroy]

I find regular carbine and rifle mil-spec springs unreliable in actual practice, and prefer the Sprinco Blue (carbine), or Sprinco Green (for A5/Rifle), and then I find the heaviest buffer that will run PMC .223 on a clean, well-lubed gun, just BARELY, and then back off 1 buffer weight.

You have feeding issues with Mil-Spec springs?