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?

[jarhead1086]

Rambler, using my 12" Noveske barrel and a QSM can with 220 MK's and WCC820 powder I got 1020 fps with 8.4 grains, 1040 fps with 8.7 grains, and 1120 fps with 9.3 grains. This is the strange part. My 16" Noveske barrel using the same powder, bullet, and suppressor shot slower with the same charge. I got 930 fps with 8.4 grains, 995 fps with 8.7 grains, and 1080 fps with 9.3 grains. Since it was my first try with this powder I only shot 1 or 2 shots of each. I will shoot 5 each next time for a better average. With regards to the PM I sent about the buffalo, subsonic Whisper will indeed kill a buffalo. We shot 2 cows that weighed about 1000 lbs (not full grown) that my friend raised. We used 220 Nosler Partitions. Both had to be shot twice because we both shot simultaneously at an agreed location between the eyes, which on a buffalo is sinuses. A follow up shot higher on the head dropped them like a rock. Live and learn, but a sub will absolutely drop a buffalo in one shot if a rookie isn't running the gun. We still have the heads, but I haven't recovered the bullets.

[A62Rambler]

I ended up getting my approved forms back on 3/15. That was about 5 weeks mailbox to mailbox. I've been so busy with another project that I haven't posted since then. My 5.56 barrel should be on it's way from being cut down early next week. I'll have to order my 300 barrel as soon as I can pay for it. Trying to start a business and funds are going to be tight for a while.

[AlcoholicusMaximus]

I just received my Model 1 sales 10.5" .300 fireball AR barrel yesterday.Haven't shot it yet,but after reading the above posts,it seems to me that the reason that you guys are getting higher velocities with shorter tubes is because there is no extra barrel to slow the bullet down. I remember reading here somewhere that the .300 whisper only requires 7 or 8 inches of barrel to achieve subsonic velocities.

[dflicker]

With a 12" LWRC AR-15, Jet Ti suppressor, 220g SMK, CCI400, gas block turned off, I'm getting a consistent 1035-1040fps with 9.2g of Accurate #9. Couldn't be happier. Now looking for a maximum load for 150 grain bullets as I have a ton of them. Any suggestions?