300 Blackout subsonic loading getting the best of me.

[Steve Donlon]

I have experimented with crimping bullets in the AR and an even crimp is very important if you use one. If your brass is not the same length you will have uneven crimps. I use an adjustable crimp die like a Lee or at least a Lee lock ring with a rubber O Ring. That way you can adjust the die down a little at a time to put a light, even crimp on your brass and it will help with velocity and accuracy. But it is more work. I don't crimp most of my bullets, only the ones with a cannelure or sometimes with slower powders where a crimp can help. And it's a separate step. It also helps to seat the bullet with a Redding Competition Seating Die so they are straight.

 

[mic2377]

Try Bullseye and Hodgdon Clays. Work down on the loads, and DO NOT double charge. It will lead to dangerous overpressure.

 

[mattri]

Whatever happened with this?

 

[DShortt]

Didn't read the entire thread.

If it were me, I'd fire a shot, wait 10 minutes. Fire another, wait 10 minutes. Repeat as necessary. And repeat the same test with the first loads.

Sounds like simply barrel heat to me.

First .308 I ever had. Bought it used. Didn't group well at all. Finally figured out it was full of copper fouling. Removed it. Wouldn't shoot well clean. Fire half a dozen shots. Wait a couple of days. It would shoot under 1" at 100.

Took me about 5 years to work that out and started my journey down the road of determining cause and effect. Long before borescopes were affordable. Wish now I still had that rifle. I'd love to see the bore.

That was 30 years ago.

Welcome to the obsession.

 

[Hoser]

Whatever happened with this?

With my 300 Whisper, nothing. I just learned to accept the fact that the first shot goes low.

My Tubb SBR in 308 has my attention now trying to find a solid subsonic load.