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300 blackout buffer weight

Mattyh921

Private
Minuteman
Feb 6, 2020
39
8
Hey all, I'm sure this horse has been beaten to death but I cant find any recent info regarding buffer weights in a 300 black pistol. Will be running suppressed exclusively and will be starting out reloading supers and eventually get into subsonics. What are the ideal buffer weights for the caliber? I don't mind switching buffers for each load if it requires.

Barrel: 8" rainier arms select 1:7, pistol gas
Suppressor: form 1; 1.5" diameter, 7" length
Not extremely gassy

Secondary question: is there a bullet/ projectile the will reliably expand at subsonic speeds and not a $1/bullet?
 
I built a 16" and 7.5" pistol upper for a friend who runs 100% suppressed with subs. Both configurations use pistol gas and a standard buffer. You should be fine with a standard buffer using pistol gas if it is ported right. Longer gas and/or a heavier buffer may reduce your ability to effectively cycle a wide range of ammo variables. If you find a standard round for your pistol, you can configure/fine-tune it to the specific round, but the pistol gas and standard buffer configuration will provide you with the greatest range/buffer of reliable cycling across a wide range of subs/supers/suppressed/unsuppressed.
 
I just looked at my most used BLK SBR, 8.5" Noveske bbl., and it uses an H2. Works fine with supers or subs, suppressed or not.

I have an AAC 16" upper but I'm pretty sure that rifle was done up with either a standard or maybe an H buffer.

I keep extras around and if one doesn't work I swap 'em around, but usually the "chart" is dead on. What I mean is there's a buffer chart on barfcom or one of those sites that has all different barrel lengths, gas systems and calibers and what buffer to use. Usually it's correct and a good place to start.
 
I run an 8” SBR (pistol length gas) with a BCM A5 receiver extension and A5H0 (3.8 oz) buffer. Shoot exclusively suppressed and it works great.

Also shoot a 16” rifle in 300BLK, pistol length gas, with a standard carbine spring/buffer that you can get anywhere - both subs and supers suppressed and not, and it also functions 100%.
 
I ended up buying a standard H buffer to start with. I have a couple st t2 in some other ARs that I'll try if the H1 isnt right
 
The conventional wisdom has always been to run a heavy buffer. But that whole idea was centered around the standard gas block.

The better option is to use an adjustable gas block. This frees you from the conventional approach in that you can run a lightweight buffer and spring. More importantly, it allows you to have one gas setting for supers and a second for subs, so your gun runs optimally with both ammo rather than a compromise which is ideal for neither.
 
I'd like to have an adjustable gas block but I have a rail that goes over the suppressor. So I'd have to take the rail off if i needed to adjust the block
 
I know the mall ninjas swoon over the handguard-over-suppressor look, but if you run a mag or two through it, the radiant heat from your suppressor is going to make your handguard so hot you can't hold it. It also makes removing the suppressor difficult. It just isn't practical.

Get a proper handguard setup that ends 1/2" to 3/4" before the suppressor and solve two problems at once.
 
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I'd like to have an adjustable gas block but I have a rail that goes over the suppressor. So I'd have to take the rail off if i needed to adjust the block

Not sure if it would be accessible with the suppressor covered by the rails, but the Odin Works adjustable gas block has its adjuster on the front end of the block, so it's accessible from the front. It also has detents, so you *should* be able to easily change between gas settings.

Also, on buffer weight: I ran an H2 buffer on my Blackout and it had some trouble cycling subs when it was unsuppressed. Sounds like you'll be running suppressed all the time, so that probably won't be an issue, but just something to note.
 
My experience has also shown a wide variation of gas port sizing between the different 300BO barrel manufacturers. Your best bet is to connect with the barrel maker, identify what they are porting the barrels to, and what they recommend for a buffer. Some have actually thought this through and did it a certain way for a reason, others are just pumping out barrels.
 
I know the mall ninjas swoon over the handguard-over-suppressor look, but if you run a mag or two through it, the radiant heat from your suppressor is going to make your handguard so hot you can't hold it. It also makes removing the suppressor difficult. It just isn't practical.

Get a proper handguard setup that ends 1/2" to 3/4" before the suppressor and solve two problems at once.
I have several rifles setup with the handguards before the muzzle. I'm not doing mag dumps, so itll be fine. The handguard setup is not in question, I'm just needing info on the buffer weight
 
My experience has also shown a wide variation of gas port sizing between the different 300BO barrel manufacturers. Your best bet is to connect with the barrel maker, identify what they are porting the barrels to, and what they recommend for a buffer. Some have actually thought this through and did it a certain way for a reason, others are just pumping out barrels.
Thanks everyone for the info