What buffer for a 18” barrel?

[Tony617]

I have ordered a fully assembled 18" chromed lined barrel. I was wondering what buffer should I use? I have a few but could buy more if these are not the ones to use. I put my second lower together yesterday evening.

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[oli700]

you'll just have to run it see what it wants, going to depend on gas port size and ammo .

 

[daved20319]

^^^ What he said. Rather than buy a variety of buffers, I just bought a set of tungsten weights and tried different combos. Only takes a few minutes to switch weights around, and can be done at the range with a minimum of fuss and tools. Later.

Dave

 

[Tomahawk67]

The heaviest buffer that will reliably lock the bolt open on the last round , using the weakest ammo you plan on firing.

 

[Tony617]

The heaviest buffer that will reliably lock the bolt open on the last round , using the weakest ammo you plan on firing.

I typically fire Federal XM193, IMI 193, or 55gr XTAC rounds. I use Speer Gold Dot for HD. I also have 1000s rounds of Wolf Gold which is .223 only. It cycles fine on factory built rifles. But I guess I will take 20 round boxes and see what is weakest ammo is. I am just waiting for the barrel assembly to arrive.

 

[titsonritz]

you'll just have to run it see what it wants, going to depend on gas port size and ammo .

This right here 100%.

.0995 is the Crane spec for an 18" rifle gas SPR, of course they use full power 5.56 ammo.

The heaviest buffer that will reliably lock the bolt open on the last round , using the weakest ammo you plan on firing.

This is the yard stick, the problem is it can get expensive testing multiple weight buffers.

I would recommend an H buffer, it may not be optimal but should be reliable.

 

[titsonritz]

I have ordered a fully assembled 18" chromed lined barrel.

Exactly what did you order? Link?

"Standard" carbine buffer are complete garbage and should be banded from earth. The lowest weight buffer should be an H.

That said, anything I build for myself has an A5 system my standard go to buffer is an A5H2.

 

[Yarome]

Of the 2... the standard should work beautifully and the H2 would likely be very much too heavy for a carbine length gas system on an 18". If you're doing an adjustable gas block you can play around with your buffer a bit, but if you're just looking for something reliable "out-of-the-box" the standard should fit your needs.

 

[titsonritz]

Of the 2... the standard should work beautifully and the H2 would likely be very much too heavy for a carbine length gas system on an 18".

I'm thinking a mid and more likely a rifle length gas system on an 18", which is why I ask about the specific item.

 

[v0lcom13sn0w]

i had to enlarge an 18" rifle gas system port to be able to run a carbine buffer once. even started a thread here about it.

i recommended a mid length to my buddy but he wanted a rifle length

 

[Tomahawk67]

I have all Vltor A5 extensions on my rifles and A5H0 thru A5H4 buffers , and they are spendy. If I was going to use a normal receiver extension and wanted to figure out the correct buffer weight without buying a bunch of buffers I would get the KAK configurable buffer and tune it to my taste.
AR-15 Configurable Buffer Kit

 

[oli700]

I have a 10.3" cabine gas that shucks all ammo with an h3 and wolf xp spring .
I have a 308 with the deep Armalite carbine extension , it runs awesome with an H3 and standard 308 spring.....Point being you won't know till ya run it .

 

[bbbass]

I'm thinking a mid and more likely a rifle length gas system on an 18", which is why I ask about the specific item.

I have an 18" with rifle length gas that runs just fine with standard buffer/spring, whatever that is. Same with my 10.5" pistol with mid length. Guess it's the ammo I'm running?

 

[oli700]

I have an 18" with rifle length gas that runs just fine with standard buffer/spring, whatever that is. Same with my 10.5" pistol with mid length. Guess it's the ammo I'm running?

And gas port size , buffer spring rate

 

[Sniper03]

A standard CAR Buffer will work just fine!
The 18 in operation is one of the smoothest compared to the Car 16s and shorter.
The Mid Length 16s are also smooth like the 18s.
03

 

[oli700]

"Standard" carbine buffer are complete garbage and should be banded from the Earth.

This is all anyone needs to know about standard carbine buffers .

 

[bbbass]

And gas port size , buffer spring rate

IDK... I dance with the girl I brought.

ARparts.com 18.5" stainless upper. El cheapo Blackhawk spring.
Hardened Arms 10.5" upper, Ebay spring.



Budget everything...

(Edit: But it all is working. lol )

 

[HB of CJ]

You are running a CAR compatible butt stock? Start out with the OEM USGI CAR buffer. Then if you want to and can afford it start having fun with the after market buffers starting with the heaviest then working your way down. Be sure to use an OEM USGI spring.

Do not run cut off industrial wire. Find and use the OEM USGI buffer spring.

If you run weird hand loads you will collect different buffers. Also miking your barrel gas port diameter is a good idea so you know what you have at the other end. Ideally you want the slowest cycling speed with 100% function. The mid length is NOT USGI stock.

 

[Sniper03]

HB
You are correct! If the guys would use Mil Spec Buffer Springs they would not have near the issues some have. And need to experiment with buffers until they got it right. They buy the coolest Chics Dig It springs and components and then wonder why the gun will not run reliably!

03

 

[powermad]

On the A5 system .
The BCM site has a kit with extension, spring and H0 buffer .
I take it that set up is for a 16" carbine gas system ?