AR 15 Pistol need help on Buffer / spring tuning

[markshere2]

Well, if it doesn't lock back then a heavier buffer isn't going to help.

Todays test reveals it is Not locking back on last round fired.
It is ejecting the spent brass to the side but not very far.

It is NOT picking up another round

I tried a different BCG - no help

Brass looks like it does when it comes out of my other ARs - no evidence of a rough chamber

Buffer spring is 39 coils and is 10 3/8" long uncompressed.

Clip a coil off and see what happens?

Has anybody ever heard of a buffer that weighs under 2.8 oz?

[marinville]

Todays test reveals it is Not locking back on last round fired.
It is ejecting the spent brass to the side but not very far.

It is NOT picking up another round

I tried a different BCG - no help

Brass looks like it does when it comes out of my other ARs - no evidence of a rough chamber

Buffer spring is 39 coils and is 10 3/8" long uncompressed.

Clip a coil off and see what happens?

Has anybody ever heard of a buffer that weighs under 2.8 oz?

It is definitely undergasssed. Changing buffers wont help. I don't know of a lighter buffer than carbine, which is what you have. Anything heavier is only going to make it worse.

If you changed the bcg, it's probably not the gas key... that leaves the gas port being under sized or gas block misaligned.

I wouldn't expect much luck from lopping off spring coils.

[Emptymag]

I know you were joking when asking if there's a buffer under 2.8 oz, but for the sake of education...

Taccom ultra lightweight - it's ONE OUNCE. I used one in my wife's lightweight build. Need an adjustable gas block to use one though.

https://www.tacticallink.com/Taccom-...-for-AR15.html

[markshere2]

I know you were joking when asking if there's a buffer under 2.8 oz, but for the sake of education...

Taccom ultra lightweight - it's ONE OUNCE. I used one in my wife's lightweight build. Need an adjustable gas block to use one though.

https://www.tacticallink.com/Taccom-...-for-AR15.html

Not joking, serious. I get back to lowest cost, least amount of dicking around.

Just because the knucklehead that made the upper did a questionable job of getting a "standard" amount of gas delivered to the bolt....does not obligate me to fix that particular facet of the gun.

Thanks for the link

That 1oz buffer is $21.00 plus shipping. I'm starting with the harbor freight 4" grinder and popping off a coil at a time to see if that can do the trick. I can get a new spring for about $4 plus shipping.

[:-)]

Not joking, serious. I get back to lowest cost, least amount of dicking around.

Just because the knucklehead that made the upper did a questionable job of getting a "standard" amount of gas delivered to the bolt....does not obligate me to fix that particular facet of the gun.

Thanks for the link

That 1oz buffer is $21.00 plus shipping. I'm starting with the harbor freight 4" grinder and popping off a coil at a time to see if that can do the trick. I can get a new spring for about $4 plus shipping.

If you lived near me I would let you try a lighter buffer spring to see if that would work or try different buffers, but It would be better to take a look at the gas port size and alignment of the gas block. See if the hole is too small or the block isn't aligned. Both are easy 10 min fixes. I had an under gassed 10.5" 300 BO, which I knew what the problem was (needed a new barrel) but I thought I would take the cheap and easy way out and just mess with the spring and buffers... It ran a little better with subs with the lighter spring but it didn't run 100%, sometimes the weaker spring would have problems with full mags and stripping rounds. I had to carry two springs with me depending on what ammo I was using. I gave up and fixed it the right way and now I don't need the spring or any other buffers I wasted time, ammo, trips to the range and money on. I run the original standard carbine buffer and spring now and it runs 100% with everything even subsonic rounds. Fix it right the first time, you will be happier.

[Hawk]

Here's a basic test you can do at home to check the gas flow for your AR.
1. Remove the upper from the lower.
2. Take a foam ear plug and plug the chamber with it (some people just use a spent cartridge)
3. Blow down the barrel from the muzzle (ya, you're kind of giving your AR a blow job)
4. Take note of how much air is coming out of the gas tube. (you can compare the flow to another AR if you have one)
5. If you feel it's lacking, you can loosen the gas block and move it around until you get the maximum flow of air.
6. If no matter how much you move the gas block around an the air flow doesn't increase, then you may need to investigate the size of the gas port in the barrel.

BTW,
Here are the length's on Rifle and Carbine buffer springs

BufferSpringInsp.jpg

Here's a good article on AR buffers and how to adjust the weight.

http://www.rifleshootermag.com/edito...on-ar15s/83752

[cdi]

You guys are killing me.
Please don't cut the action spring.
The way to correct the issue is to get it to someone who knows what they're doing.
Gun needs a hands on inspection.

[markshere2]

If you lived near me I would let you try a lighter buffer spring to see if that would work or try different buffers, but It would be better to take a look at the gas port size and alignment of the gas block. See if the hole is too small or the block isn't aligned. Both are easy 10 min fixes. I had an under gassed 10.5" 300 BO, which I knew what the problem was (needed a new barrel) but I thought I would take the cheap and easy way out and just mess with the spring and buffers... It ran a little better with subs with the lighter spring but it didn't run 100%, sometimes the weaker spring would have problems with full mags and stripping rounds. I had to carry two springs with me depending on what ammo I was using. I gave up and fixed it the right way and now I don't need the spring or any other buffers I wasted time, ammo, trips to the range and money on. I run the original standard carbine buffer and spring now and it runs 100% with everything even subsonic rounds. Fix it right the first time, you will be happier.

WAAAAAAAAAAAAAAYYYY too late for that.

trimming spring - no help.

Immana takeit my gunsmif.

[markshere2]

Ok - the gas block is a very nice looking high speed low drag aluminum piece with 4 picatinny rails on it.

We pulled it and the barrel hole is clear and the tube is clear, but the gas burned the shit out of the aluminum gas block.

Lotsa gas escaping = not enough oomph to work the action correctly.

Steel gas block on order .

[DucatiRon]

Himmmmm. I do believe someone somewhere mentioned it was undergassed.