300 BLK reloading adventure

[C'mon man!]

Lilgun fan here too. I tried accurate #9 and Lilgun to make the quietest subs while still locking back on an empty mag in my 8” AR and staying just below the speed of sound. My best result was 8.5 grains Lilgun with 220gr Berry’s bullets 2.1” OAL, 1050 fps.

 

[Control for Smilers]

ok, I am about to add 300 blackout to the calibers i load for. I have a subsonic question. I have a LOT of 175gr projectiles for my .308 bolt guns. I was looking at Sierra's 300 aac load data...

I have like 7 pounds of imr 4198 that i use for 20VT. Is there any reason to not try some 175gr subs? ****s and grins, going to pick up some 220's or 208's eventually, but in the meantime...

any issues I am looking at? 99% sure that load listed will work action. I watched some vids of 4198 300aac load development on youtube to get a feel for velocity and cycling with that powder subsonic. any feeding issues? baffle strikes? going to potentially use sierra 175's, nosler 175cc's, and nosler 175 rdf's. thanks in advance for any advice. I would just load and test, but it is in jail...

 

[adrianrog]

i have a bunch of 180's and thought I'd find a good subsonic load with those bullets and eventually gave up. I had velocities all over the place and crazy groups. Shot those same bullets supersonic just fine. I've had pretty good luck with Sierra 220 MK's. Nothing spectacular accuracy wise, but 1-1.5" is doable. I'm shooting a 10.3" barrel. Loaded some of those over 10 grains of H110 just yesterday.

 

[Control for Smilers]

What twist barrel are you using? and thanks for the info

 

[adrianrog]

What twist barrel are you using? and thanks for the info

Mine as a 1:7 Ballistic Advantage

 

[1006]

Probably will not cycle an AR at sub sonic loads

 

[Control for Smilers]

which load? I will be using a 1:5 twist barrel.

 

[1006]

The twist won’t matter when considering weather or not an AR will cycle. You have to use enough powder to make the gas required for function. Anything under 200 grains will require too little powder to remain subsonic.

Now this is just my opinion: In the 300BLK there really is not much use for bullets between 150 and 200 grains, as they are not capable of performing well as either subsonic or super sonic, unless you use a gun that does not require gas pressure from the load to function.

1:5 is something new to me. Just guessing it is for the heaviest of bullets at sub sonic speeds.

 

[Control for Smilers]

Probably will not cycle an AR at sub sonic loads

which load are you referring to?

 

[1006]

Sorry: any load at subsonic velocity with bullets lighter than 200g.