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nic
06-01-2009, 8:37 AM
Hi guys,
Here's sort of a random question. I was browsing Arfcom and some guys had recommended using a 9mm buffer in a 5.56 carbine-gassed AR to reduce felt recoil, fix timing issues and change ejection patterns. I understand the physics/principle behind doing this and how it would affect the rifle's timing, but I was curious as to whether the extra mass of the 9mm buffer would damage the rifle in any way, particularly when used in conjunction with the higher-pressure carbine gas system.

Any thoughts?
-Nic

Bladewurk
06-01-2009, 9:57 AM
Carbines are overgassed so these work alright, just don't use the extra long length ones like Slash in a Carbine buffer tube..the RR or Colts work fine usually.

Alot of guys use standard rifle buffers also in A1 or A2 stocks with rifle length buffer tubes

deez
06-01-2009, 10:18 AM
Nic,

I run a 9mm buffer in my 16" 5.56mm carbine, works fine.

No issues at all...

nic
06-01-2009, 10:31 AM
Thanks for the responses, fellas.
Deez, do you ever have cycling issues with slightly weaker or more anemic .223 loads?

deez
06-01-2009, 11:05 AM
Thanks for the responses, fellas.
Deez, do you ever have cycling issues with slightly weaker or more anemic .223 loads?

I've had no issues with Wolf, which is pretty much all I plink with.

Cobrafreak
06-01-2009, 11:13 AM
I use a 9mm buffer with my 16" carbine as well. It increases the lock-time so that the majority of the gas stays in the barrel pushing the bullet down range where it should. My AR seems to actually run cleaner than before because it eliminated the over gassing problem. The last few times I have shot it I didn't really need to clean anything in the action. I just pushed a patch through the barrel and put it in the safe.

nic
06-01-2009, 12:09 PM
Thanks guys. I will order an RRA 9mm from Riflegear!

Desert_AIP
06-01-2009, 12:12 PM
The increased mass should not increase wear and tear because it is moving at a slower speed.

Untamed1972
06-01-2009, 3:26 PM
So does it actually reduce felt recoil? Help keep you on target between shots?

Desert_AIP
06-01-2009, 3:36 PM
The higher reciprocating mass actually increases recoil, that extra moving mass still stops abruptly at the end of the receiver extension.
But, it occurs over a longer time period, so it feels smoother.
More like a push than a shove.

The primary benefit is to reduce wear and tear on internal parts, particularly with a carbine gas system.

NSR500
06-01-2009, 3:38 PM
If you go heavier with your buffer make sure you upgrade the spring as well.

nic
06-01-2009, 3:51 PM
^^^
Upgrade to what? Is there a heavy spring?

NSR500
06-01-2009, 3:54 PM
Wolff, Tubb, and Larue have upgraded springs.

Desert_AIP
06-01-2009, 4:30 PM
I'm not sure I agree with the spring advice.
The carbine spring is already heavier than the rifle spring.

If you add weight AND a stiffer spring it may not have enough recoil force to operate the action reliably.

Plus a stiffer spring will drive the BCG and now heavier buffer forward with higher velocity, which will impact with greater momentum and force the muzzle down when the bolt locks.

Try one mod at a time.


The only gun I run a Wollf spring in is my 45ACP blowback.

eighteenninetytwo
06-01-2009, 5:01 PM
Does somone have a solid description and or diagram of how these buffer thingies work? I have my first AR being delivered to the FFL tomorrow (very very excited thank you) so I will of course be looking to add, upgrade imporve and tinker as soon as possible.

jumbopanda
06-01-2009, 5:02 PM
I'm not sure I agree with the spring advice.
The carbine spring is already heavier than the rifle spring.

If you add weight AND a stiffer spring it may not have enough recoil force to operate the action reliably.

Plus a stiffer spring will drive the BCG and now heavier buffer forward with higher velocity, which will impact with greater momentum and force the muzzle down when the bolt locks.

Try one mod at a time.


The only gun I run a Wollf spring in is my 45ACP blowback.

Agreed, there is no reason to install a heavier spring if you're using a heavy buffer. A standard carbine spring is indeed already heavier than a rifle spring.

NSR500
06-01-2009, 5:09 PM
Some spring upgrades are not done just because of the weight. Some upgrades are done for consistency/repeatability, and reliability.
Every gun is different so YMMV, but I look at things like I do cars. If you run a hotter cam, you've got to at least do the springs and retainers too.

Desert_AIP
06-01-2009, 8:37 PM
Does somone have a solid description and or diagram of how these buffer thingies work? I have my first AR being delivered to the FFL tomorrow (very very excited thank you) so I will of course be looking to add, upgrade imporve and tinker as soon as possible.

In the simplest terms, the buffer stops the rearward travel of the bolt carrier group so it doesn't crash into the rear of the receiver extension or the aluminum receivers.

The mass of the buffer primarily controls the rate of the rearward travel of the bolt carrier group during recoil, which affects cyclic rate.
It also affects unlock/dwell time. (Randall am I using those terms correctly?)
The polymer bumper on the end absorbs the impact with the end of the receiver extension and prevents it from damaging the extension.
The reciprocating weights inside seat the bolt with an extra "shove" after the spring returns the bolt carrier group to battery.
Notice the 9mm buffer doesn't have reciprocating weights inside. It's designed for use on blowback 9mm carbines.
However, the reciprocating weights are only really an issue for full auto guns to prevent bolt bounce.
That's why you can use a 9mm buffer in a semi gun. But you can't reliably use one on a full auto (non pistol cal) gun.

But, I do use the H buffers vs. the 9mm in my semis. In a really dirty gun that extra shove help seats the bolt fully into battery.

http://ar15barrels.com/tech/buffer-construction.jpg

RECCE556
06-01-2009, 9:16 PM
Yeah, like Desert said, I don't recommend the heavier spring upgrade. The ONLY spring upgrade I would recommend is going with a CHROME SILICON, STANDARD WEIGHT spring, not a extra power spring.

Also, if your gun is running WOLF with a 9mm buffer, your gun is WAY overgassed or your spring is kaput. In over a dozen 14.5" Colt M4 uppers I've tested, anemic ammo (like Rem. UMC) will fail to bolt lock on the last round with a 9mm buffer with a standard carbine spring and a standard weight chrome silicon spring...they would also fail to cycle another round a lot of the time. So unless your system is overgassed, I wouldn't recommend 9mm buffers.

I run H2 buffers in all my Carbine gas uppers/builds and it works great even cycling weak rounds but you have to really test out your upper with different ammo to see what combination makes your rifle fail and then bring it down a notch or two.

slappomatt
06-01-2009, 9:47 PM
I have a colt steel 9mm buffer in my 16" carbine for a while now. I have tried it in several guns from a 11.5" pistol to a 16" middy and it cycled great in all guns. Highly recomended. I just bought a larue extra power spring to try out with it as well. I was hoping to take it out to the range this past weekend but didnt get the chance. Ill report back when I can. as for the buffer alone it really reduces the felt recoil alot! Everyone that has tried it has wanted one.