300BLK Pistol build question

[The Norseman]

So I've done some internet searching and some searching here and have not found much of an answer to a question or two rattling around in my head.

I just found 5.5 oz buffer in my box or AR parts as well as an 11" buffer spring (37 coils). I've concluded these are a 9mm buffer and a carbine length spring. I am planning a pistol lower build, using a 7.5" pistol buffer tube. I'll be using a 10" 300BLK upper on the build (with pistol length gas tube). Long windedly, can I (should I) use the 5.5oz buffer? Trade it for an H2 buffer? Any experience or thoughts with that type of set up?

On another note, I function tested the upper on my SBR'ed lower and it was fun to shoot. The 147 gr factory ammo cycled fine and now I'm looking forward to shooting subs through my YHM Ti Phantom....

Norseman

[DFBrews]

My10.5 uses a standard buffer and spring cycles everything I have thrown at it

[Great-Kazoo]

I try parts on hand before spending money, for something that may not be needed.

[Skully]

I try parts on hand before spending money, for something that may not be needed.

"Wise so, you are."

Yoda

[The Norseman]

Thanks for the input....I'm figuring the spring is the right item. The buffer was more what I was curious about. I'll try it for sure to see how it goes.

[ray1970]

I say if it ran ok on one lower I would just put the same parts in the new lower and be done.

[fullmann]

Make sure that buffer isn't the longer type for 9 mm.

It it may not be physically able to cycle far enough back to eject and load properly.

My 10.5" pistol gas 300 works fine with a standard buffer and spring. Supers and subs.

[The Norseman]

Fullmann...any idea what length is on 9mm vs. 5.5oz carbine buffer? I'll search but if you know that'd be helpful. Thx!

Norseman

Ps here's upper on my SBR

[fullmann]

I can measure them tonight when I get out of work.

[fullmann]

Sorry it's a little late.. But here is the pic of my 9mm buffer in comparison to a standard buffer.

I weighed it and apparently mine is about 8 oz. so I may have steered you incorrectly on the 5oz buffer.

FWIW, the other buffer shown is from my 10.5" 300blk build and it works fine with supers or subs.

anyway, here's the pic of the 9mm buffer.