AR Buffer question

[hpdrifter]

I got a side charging AR. 6.5 grendel. It's got a rifle length gas tube. I put a carbine buffer tube and a Strike industries flat wire spring in it with an H2 buffer.
Runs fine, not a problem at all with it, except it won't lock back on last round. It'll lock back fine manually; by hand.
I'm not gonna change the spring, I like the flat wire spring.
I have always heard the the Grendel is over gassed....but it doesn't appear so here. I was wondering if a lighter buffer might help the lock back issue, or maybe a heavier...to maintain any momentum it possesses.

Any ideas.

[RifleBowPistol]

So when you say, it will lock back manually, what are you doing to get it to lock back? Will the bolt catch hold the bolt back, if you pull the bolt back, with the charge handle, with a empty magazine in the gun? Or do you have to push the bolt catch to lock the bolt back?

If you can pull the bolt back, with an empty mag in the gun and the bolt locks back, then yes, you have a problem with either lack of gas, or buffer/buffer spring issue. Basically the bolt is not traveling as far back as it should, like you seemed to have figured out. Could be lack of gas flow, which is what it sounds like. But it might be a buffer spring problem.

[Raider4044]

The rifle length gas system probably cuts back on the gas enough that it may not need the heavier buffer.

Send me your address. I think I’ve got a standard buffer that I’ll mail you to see if that fixes it.


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[Clay C]

Try an H buffer.

[andre3k]

The rifle length gas system probably cuts back on the gas enough that it may not need the heavier buffer.

Send me your address. I think I’ve got a standard buffer that I’ll mail you to see if that fixes it.


Sent from my iPhone using Tapatalk

I agree with this. With the rifle length gas system you probably don't need the h2 buffer.

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[hpdrifter]

If you can pull the bolt back, with an empty mag in the gun and the bolt locks back, then yes, you have a problem with either lack of gas, or buffer/buffer spring issue.

Yep, that's what I meant.

The rifle length gas system probably cuts back on the gas enough that it may not need the heavier buffer.

Send me your address. I think I’ve got a standard buffer that I’ll mail you to see if that fixes it.


Sent from my iPhone using Tapatalk

I appreciate to offer, very generous of you. They aren't that expensive and the shipping would probably be more than the buffer. Thanks.

Try an H buffer.

I agree with this. With the rifle length gas system you probably don't need the h2 buffer.

Sent from my SM-S918U using Tapatalk

Think that is what I'll do.

Thanks for your time, replies, and knowledge!

[ATI]

I got a side charging AR. 6.5 grendel. It's got a rifle length gas tube. I put a carbine buffer tube and a Strike industries flat wire spring in it with an H2 buffer.
Runs fine, not a problem at all with it, except it won't lock back on last round. It'll lock back fine manually; by hand.
I'm not gonna change the spring, I like the flat wire spring.
I have always heard the the Grendel is over gassed....but it doesn't appear so here. I was wondering if a lighter buffer might help the lock back issue, or maybe a heavier...to maintain any momentum it possesses.

Any ideas.

I don't know much about side charging ARs, but I had this issue and changed to a H3 Buffer and it solved the issue. Going lighter on the Buffer does not help, because the BCG is moving too fast to catch and lock, you want to slow down your BCG with a heavier Buffer or a Stiffer Buffer Spring... Also what type of BCG are you using?

[Artos]

Adding a suppressor will fix it...

[ATI]

Adding a suppressor will fix it...

Then you'll realize you need an adjustable gas block or a stiffer buffer spring or both

[imyomama]

I don't know much about side charging ARs, but I had this issue and changed to a H3 Buffer and it solved the issue. Going lighter on the Buffer does not help, because the BCG is moving too fast to catch and lock, you want to slow down your BCG with a heavier Buffer or a Stiffer Buffer Spring... Also what type of BCG are you using?

the answer is not that simple ... first determination is to find out if your bolt is going to slow or too fast ... assuming it's too fast is just that ... assuming ..

so first, shoot one round ... does it eject 2 feet or 15 feet and in which direction .. that tells you if it's fast or slow

if it's slow , first pull the gas block and look for the burn mark on the hole , you could have it misaligned.
if it's not misaligned , then you need to speed up your bolt by reducing weight on your buffer

if you plan on running suppressed and it's undergassed , the additional back pressure from a suppressor may allow it to lock back ... depending on it's design

if everything checks out and it's overgassed and too fast , use a heavier buffer, or go to an adjustable gas block to restrict the gas , which will also make it run cleaner and a better way IMHO...

my 2c.

[imyomama]

one last thing .. re-reading your post about the flat wire spring.. is that spring for a carbine buffer tube or for a rifle buffer tube ... if it is the later in a carbine tube , your spring may be over compressed and not much will really fix that ... in that case , try to swap out the spring before you do anything else and see if the problem goes away ...

[ATI]

the answer is not that simple ... first determination is to find out if your bolt is going to slow or too fast ... assuming it's too fast is just that ... assuming ..

so first, shoot one round ... does it eject 2 feet or 15 feet and in which direction .. that tells you if it's fast or slow

if it's slow , first pull the gas block and look for the burn mark on the hole , you could have it misaligned.
if it's not misaligned , then you need to speed up your bolt by reducing weight on your buffer

if you plan on running suppressed and it's undergassed , the additional back pressure from a suppressor may allow it to lock back ... depending on it's design

if everything checks out and it's overgassed and too fast , use a heavier buffer, or go to an adjustable gas block to restrict the gas , which will also make it run cleaner and a better way IMHO...

my 2c.

Agreed, but most short guns are are over gassed and the BCG is moving too fast to lock back and based on my own experience it's more likely that it's moving too fast.

You can put your mobile on the side, in front of the ejection port and record the BCG (in Slow Motion Video setting) that'll give you a good image if the BCG is even reaching all the way back or not.... if it's NOT, then you're under gassed and it's not even going all the way back to lock....

It could also be your magazine, try different magazines, but I think it's a Problem with the speed of BCG going too fast and has to be slowed down (based on my short gun case) and I used a heavier Buffer...

heck, I'm going to stop here, because the more you think about it the more technical and over analyzed this can get...

For now, Just make sure you're NOT using an skeletonized BCG (light BCG), use a regular BCG and try a heavier and then a lighter Buffer to see what happens

[imyomama]

oly crap ... i re-read it again ... you have a rifle tube and a carbine spring .. buy the spacer !

they make a drop in spacer for just that .. if everything else checks out .. that's it!

[imyomama]

It's got a rifle length gas tube. I put a carbine buffer tube
Any ideas.

problem solved .. get the spacer!

[ATI]

oly crap ... i re-read it again ... you have a rifle tube and a carbine spring .. buy the spacer !

they make a drop in spacer for just that .. if everything else checks out .. that's it!

yes, I missed that too...


Decide what you want and either change your tube or your spring to be in spec, or use the spacer as hesyomamma said. If your spring is too short, then your BCG may not be functioning correctly to lock

Good luck and let us know what happens.