Late to the party on .300 AAC blackout.

[NWcollector]

I'm late to the party with this. I've known people who don't like using bolt guns who own/use an ar-10 or fn scar in .308 (or 6.5) for hunting elk/deer or long distance shooting and own/use an ar-15 or two for everything else rifle related.

Where does the 300 AAC Blackout fall into play? I've heard people talk about it as using it with an AR pistol suppressed - which sounds pretty niche. What is the attraction and where does it shine compared to the classic 5.56 or the ar-10? Just trying to get some orientation. And for those who enjoy it, what length barrel and build/brand do you like the most?

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[Nosferatu]

Broad comparison:

.300BLK subsonic = 9x19mm
.300BLK supersonic = .30-30 Winchester

It fires from a 5.56/.223 length action, which is shorter than a .308Win/6.5CM action.

 

[Nwcid]

You have to look at the history. The .300 BO start at a wildcat called .300 Whisper and the main goal was to have a reliable auto loading rifle that fired subsonic ammo and used every standard part of an AR-15 besides the barrel.

Largely the .300 BO was great marking with a truly small niche.

Just remember that the AR platform has been chambered in well over 50 different calibers.

 

[Nick Burkhardt]

I do not own a 300 BO yet, but my understanding is that it has an advantage with short barreled rifles or AR pistols since it uses faster burning pistol powder so you don't get the noise and flash of unburnt powder igniting after it exits the barrel which is typical with 5.56 with shorter barrel lengths.

 

[ODG_Chad]

I do not own a 300 BO yet, but my understanding is that it has an advantage with short barreled rifles or AR pistols since it uses faster burning pistol powder so you don't get the noise and flash of unburnt powder igniting after it exits the barrel which is typical with 5.56 with shorter barrel lengths.

This is what I understand, as well. That 300BO was designed to be quite effective out of a shorter barrel, though this isn't necessary, of course.

I've also seen it mentioned numerous times that the ease of switching between subsonic and supersonic makes it desirable for some people. Keep mags on hand loaded with subsonic to shoot suppressed and keep things relatively quiet, while also keeping mags on hand loaded with supersonic to reach out a bit further with nothing other than a change of mag.

With all that being said, I personally have zero experience with the cartridge.

 

[Nwcid]

loaded with supersonic to reach out a bit further with nothing other than a change of mag.

Do not forget a change in aiming point. Subsonic .300 BO has a trajectory similar to .22 LR.

 

[Nick Burkhardt]

My interest in 300 BO is to get rifle terminal ballistic performance (2200+ fps) out of a 10.5" barrel AR pistol without blinding myself or deafening everyone in my house or car.

 

[ODG_Chad]

Do not forget a change in aiming point. Subsonic .300 BO has a trajectory similar to .22 LR.

Valid point, for sure.

 

[saxon]

i can load subsonic hearing safe no suppressor with last round bolt hold open.
i can load super and sub that at 34 yard have a poi of 2" difference for close up critters.
nikon made a scope for super and sub that if you know your drop, a few clicks and your on target out to 400 yards depending on your choice of bullet.

ballistics? how deep do you want to dive? 5.56 shoots flatter, but 300 has it beat for FP on target.

and on and on,

a tool is a tool it all depends on what you want to get done

 

[DB is Here]

Built mine for road travel in pistol format. 10.5 barrel and 150grain vs 55 grain packs a wallop.

It's a solid performer out to 200 yards.

 

[JuglansRegia]

I am shooting 220-245gr powder coated right at the speed of sound on a hot day but subsonic when it's cold. Way more energy than a 9mm, mags are 30 rounds, cheap, readily available and don't look dorky like glock mags in an AR. I make brass from banged up 5.56 and it only burns 9gr of H110/W296 a shot. Accuracy is better than any other handgun l own.

 

[NWcollector]

I notice a few replies talk about shooting it as a pistol with a 9 to 11 inch barrel. Is this something that can be shot with two hands and without a pistol brace or stock? It seems as if with subsonic ammo you can fire it without a suppressor (and at least save one stamp). Or does it really need that stock to be functional?

Also, Is there a sweet spot for that barrel as far as ballistics go? I've seen rattlers at around 6 inches and I've seen 16 inch spear mcx as well.

 

[JuglansRegia]

If you are shooting subs, 10" is probably the ideal barrel length. Lighter projectiles usually benefit from a longer barrel there isn't much case capacity so don't expect a huge difference.

 

[Loc]

This was incredibly helpful to me on the subject of ideal 300 BO barrel length depending on ammo load.

View: https://youtu.be/4VNl7QXykUY?si=HV2frusbrkiHvEHO

 

[edzz]

Don't forget one of 300 Blackout's disadvantages, being as it is a simple barrel change from 5.56 if your range day includes shooting AR,s chambered in 5.56 and 300BLK in the same session its a good idea to have magazines that are dedicated to each cartridge. 300BLK will chamber in a 5.56 gun. All my Blackout magazines are Lancer and my 5.56 magazines are Magpul for easy identification.
Remember, loading a 300BLK in a 5.56 is a recipe for disaster...

 

[ilikegunspdx]

I notice a few replies talk about shooting it as a pistol with a 9 to 11 inch barrel. Is this something that can be shot with two hands and without a pistol brace or stock? It seems as if with subsonic ammo you can fire it without a suppressor (and at least save one stamp). Or does it really need that stock to be functional?

Also, Is there a sweet spot for that barrel as far as ballistics go? I've seen rattlers at around 6 inches and I've seen 16 inch spear mcx as well.

% energy loss compared to 18" barrel.blue line is 300 BLK others are .223. Percentage annotations are for .223. It's always a question of how much velocity/energy you want to give up for the handier size.

B1112E65-6A6F-448D-9CE4-F493DCC3A67F.jpeg

• ilikegunspdx
• Apr 14, 2024

Comparison of muzzle energy levels of some different calibers for 12.5" barrel length

0A427FC5-E06B-48FC-8FD0-8BC33208FEF2.jpeg

• ilikegunspdx
• Apr 14, 2024