Best Powders for 12" 300-221

[A62Rambler]

I've been gathering all the loading info I can for my SBR project. What are powders that would work best? Barrel will be 12" with pistol gas port. I want to do both 125gr supersonic and 190 to 220gr subsonic and will be using a 762 YHM Phantom. I didn't want to hijack another thread I read.

[cav_scout_tj]

I too have an SBR barrel on the way. While I don't have any true experience yet, my research says the faster burning powers in 300 whisper should work best. That would be slower to faster: 296, Lil Gun and 2400. I stocked up on some Lil Gun and 296. I have some 2400 left over from 44 mag loads.

I'll let you know when my barrel shows up. I have a 9.5" coming.

[JFettig]

I have a 10.5 coming soon for a pistol, I have some hogdon 110 that I plan on using initially. I will primarily be shooting supersonics, 147-165 and some smaller.


Jon

[A62Rambler]

Well, a call to the ATF and I've got time to wait. They guessed it would be 6 weeks before it even gets to someone to start the approval process. The guy told me it would be May before I got it back with a stamp. It's going to be a long wait. On the bright side, I should have had plenty of time to gather everything I need. I guess I'll try AA9 and maybe N110 from Vhitavouri. By the time I get it you guys will have loads worked out and can tell me how well H110, 2400, 296 and Lil Gun work.

[jarhead1086]

I just got an SBR permit back about 2 weeks ago. It took 5 weeks from mailbox back to my mailbox. Sure beats the old Chicago days waiting 8 months or longer on Forms. I fired my 12" AR tonight for the first time without my chronograph since I was mainly testing function. It seemed to go super on loads that were sub in my 16" using AA#9. I tried 8.9 & 9.0 grain charges and both cracked. I will shoot some more loads across the chrony this weekend and share. BTW my 16" was a Shilen and the 12" is a Noveske and both 1:8's. It was also colder outside by 30 degrees compared to when I worked the other load up. Which could account for a slower speed of sound. Remember speed of sound = 49.06 times the square root of (T + 459). Temp is in good old Fahrenheit. Every powder lot and barrel is a little different. I used a titanium QSM suppressor too which is tighter than the Thundertrap so I suspect some more freebore boost too. I'm gonna hopefully find out this weekend.

[A62Rambler]

Hey Jarhead,
What bullet weight were you using?