length of 9mm buffer vs carbine buffer

[JoeBobJoe]

I thought the 9mm buffer was just a H3 but in a solid piece steel design.
I figured it be better at slowing unlocking on a upper that's over gassed a bit.

[lysander]

Generally, about 3/4 inch longer than a carbine buffer, exact numbers may vary.

[One More Time]

9mm buffers are the same length as A5 buffers.
To run one you will need an intermediate tube.

[Clint]

The whole point of longer buffers in 9mm applications is to reduce the stroke and limit the over travel past the bolt catch.

Longer 9mm buffers should be used with standard CAR receiver extensions in 9mm applications.

Now that VLTOR came out with stainless versions of the A5, they're really the first and last choice for most 9mm applications.

https://www.vltor.com/shop/ar/buffer-components/vltor-a5-buffers-stainless/

https://media.mwstatic.com/product-images/src/Primary/592/592930.jpg?imwidth=680

9mm buffers are the same length as A5 buffers.
To run one you will need an intermediate tube.

[One More Time]

I used an A5H4 buffer in my 9mm, carbine tube and rifle spring.
When I ordered another A5H2 buffer I seen that they now have dedicated 9mm buffers.

I got out of the 9mm but still use the A5H4 buffer for testing new builds.
If it locks back on an A5H4 buffer I order a BRT gas tube sized for an A5H2.

I put one on a Faxon barrel and should be testing that out today.
It was locking back with the A5H4 and with the .081" gas port it probably would have locked back with one of their heavy 9mm buffers.

[JoeBobJoe]

Thanks. I didn't realize that the 9 mm varies in size that much.
I am thinking or running a Luth AR, 9 mm buffer 5.4 oz & it say 3.25 inches, I think that should be ok in either a 9 or .223 with carbine receiver extension. It's also a solid buffer not a dead blow. I'll also be using to test for reliability.

[One More Time]

You can only use that buffer with a carbine extension on 9mm

For 5.56 it would need an A5 intermediate extension.
And at that point you are making an A5 action so just use the appropriate Buffer and a rifle spring.

Vltor and BCM have the extensions.

A .308 carbine tube is also intermediate length.
I used the one from my SR762 on my 14.7" middy with an A5H2 buffer and rifle spring.

An A5H2 is about the same weight as a Rifle buffer.

[Clint]

The 9mm blowback setup doesn't have a separate bolt out the front, so the bolt is effectively shorter.

To compensate for this, a longer buffer or a buffer spacer is used.



Thanks. I didn't realize that the 9 mm varies in size that much.



A short, solid buffer is a poor choice for a 9mm.

Excess over travel will tend to break bolt catches.

There is no dead blow effect to stop bolt bounce.

It's actually not heavy enough, so bolt velocity will be higher than needed.


Do yourself a favor and grab the VLTOR A5SH2.

It's ~8oz heavy, 4" long and has the equivalent of 6 steel weights for dead blow effect.

https://www.midwayusa.com/product/1022052732?pid=737224



I am thinking or running a Luth AR, 9 mm buffer 5.4 oz & it say 3.25 inches, I think that should be ok in either a 9 or .223 with carbine receiver extension. It's also a solid buffer not a dead blow. I'll also be using to test for reliability.

[JoeBobJoe]

You can only use that buffer with a carbine extension on 9mm

For 5.56 it would need an A5 intermediate extension.
And at that point you are making an A5 action so just use the appropriate Buffer and a rifle spring.

Vltor and BCM have the extensions.

A .308 carbine tube is also intermediate length.
I used the one from my SR762 on my 14.7" middy with an A5H2 buffer and rifle spring.

An A5H2 is about the same weight as a Rifle buffer.

Ok, Thank you. I was looking into the A5 recently. I have a upper that I was thinking of putting a rifle length extension on, but I do prefer the adjustable stock & different stock options the A5 has with it taking all carbine tube length stocks.

[One More Time]

Getting an A5H2 buffer is hit and miss.
I got lucky the last time I wanted one and it was in stock, I thought I was going to have to swap my one and only between rifles.

I got the first one way before the covid BS hit and wound up having to get the whole stock kit in Forest Green to get it.
There was 2 black and the green in stock, by the time I thought about it and hit add to cart the green was the last one.
I had been on back order for a while for just a buffer.
But it is a nice set up.

[rifleman8]

JoeBob - I have an extra BCM A5 receiver extension ( what they now call "intermediate" on BCM website ), it is like new with BCM rifle spring. It has a small blemish that does not show when it is installed. It is yours for free if you want it - for your quest to get that upper to behave. That way you got lots of options for buffer weight - just be certain the buffers you try are suitable for 5.56mm in that length receiver extension ( I know nothing about 9mm buffers ). I use one - good piece of gear. I like it because Magpul MOE or CTR stocks close all the way on them if you use their extended butt pad.
I would think that would help get your bolt velocity where you want it, if it's not already. You may still have something with the ejector / extractor that needs improvement to get the reliability where you want. I don't like when empties dribble out lazy like you were describing in earlier thread, but that maybe just my OCD.
Anyway, let me know if interested