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what spring and buffer do you want for a 300blackout pistol


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H3 in Dawn Marie's build, with a Rainier Match 14.5" pinned barrel, carbine gas system.  That thing has some gas port magic going on, cycles factory supers fine, and run my 150gr handloads great.  ((Hornady 150gr HPBT, cut down and resized 5.56 NATO cases, CCI 400 primers, 16.1 grains H110))


Had to work my 16" carbine gas NEMO Arms barrel over, in the buffer department.  I went MagPul MOE Rifle stock and rifle buffer system on it.  Wouldn't cycle some ammo, and wouldn't reliably cycle my 150gr handloads.  The Rifle buffer is what is was.  I had to lighten that thing up to about H weight to get it to cycle everything and lock back on a single round/last round.  I'm going to convert that one over to the Spike's rifle receiver extension spacer, and just run a standard carbine buffer in it, with the trusty Armalite carbine spring.

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Thank you gentlemen I now have a good idea of where to start, I still need many parts but i decided to build this one from the ground up I need to learn how and it will be entertaining for you guys with all my dumb questions..... now back to the smoker it is full of salmon...... :)

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with the trusty Armalite carbine spring.

I love this kind of talk. Brings a happy tear to my eye. :'(


Actually....all kidding aside. Do you think that any of us would bust your balls on this Magwa? Well.....you're right. We probably would. But in a friendly, loving way. <laughs>

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  • 7 years later...
8 hours ago, Sdl said:

I have a 10.5 inch 9mm upper that I want to convert to .300 blackout. If I stay the same length can I use the same gas system? Swap the barrel and BCG and maybe the buffer? Any help would be appreciated. 

Please drop by the introduction section and tell us a bit about yourself.

No need the post the same question in multiple threads.

I answered you question in the other thread.

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10.3" barrel, H2 buffer and standard power flat wire carbine buffer spring. Don't do as I first did and just grab any spring from the parts box. It was a rifle spring with too many turns and it didn't work. What I have works with supers and subsonic, but I load for the firearm. I have purchased some commercial subs (S&B) and they didn't work.

Re: the long spring, I clipped off the excess turns and amazingly it worked fine. Go figure.

Edited by BrianK
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