Buffer that will work with .223 (super) and 300b/o Subs?

[thisguy65]

Is there one buffer that will work in .223 upper in 10.5" shooting supers and 300b/o shooting subs in 10.5" ?.

[44Dave]

Wasn't 300blk designed to be used with a regular carbine buffer?

[jackblack73]

AAC recommends an H2 with carbine spring for their 9" uppers. I've found that works well, and also works well with my 11.5" 5.56 from BCM. What works well for you will depend on the size of the gas ports for your barrels. But if it were me, I'd start with an H2.

[The FNG]

I use a 16" barrel for my 300BLK, but it's pistol gas. Uses the same lower as my .223 which uses an A5H2. I have not used subs yet but works well with supers.


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[Auto-X Fil]

That depends entirely on gas port size. I run an 8" 300 BLK with subs and the damn gas port is so big I needed to put an SLR block on it to cycle my 240gr handloads. Even with an A5-H4 the bolt was out-running the magazine half the time.

With 11.5" 223 properly gassed, and 8" BLK subs properly gassed, both run great with my A5, any buffer from H0 to H4. The BLK feels best with an H4, but it runs fine with an H0.

[Eurodriver]

I had an AAC 9" 300BLK upper (all 4 conditions), a 12.5" BCM, a 20" BCM, and an 11.5" BCM (both supp and unsupp) all work with an A5H0.

[thisguy65]

That depends entirely on gas port size. I run an 8" 300 BLK with subs and the damn gas port is so big I needed to put an SLR block on it to cycle my 240gr handloads. Even with an A5-H4 the bolt was out-running the magazine half the time.

With 11.5" 223 properly gassed, and 8" BLK subs properly gassed, both run great with my A5, any buffer from H0 to H4. The BLK feels best with an H4, but it runs fine with an H0.

Whats your load for 240's subs
?

[Auto-X Fil]

Crap, I actually forget. I think I settled on 10gr N110.

[tom12.7]

The A5H0 may work ok, but there's a lot going on. More mass in the buffer can help many, but not all, depends mostly on the mix of parts involved. There's more than a few reasons that I prefer systems that support the A5H2 as a baseline.