Unstable bullets in 300 blackout

45 for me · Jul 16, 2016

I have a Liberty Leonidas 300bk upper. It's an 8 1/2" Lilja barrel with a large integral suppressor. 1/8 twist

I am shooting Missouri bullet companies lead, polymer coated, 245gr bullets

I have shot several hundred of these so far with no issues, but I noticed after doing a rapid fire on an already warm firearm, some of the bullet strikes were horizontal at 20yds. That wasn't happening during slow fire, and I have shot accurately with these loads at 100yds.

The load is 12gr with accurate 1680. These are right at the 1000-1050fps range.

Thoughts?

Twodogs · Jul 16, 2016

I would drop down to a 200-208 gr bullet or try leatherhead 245's they are sized to .311 and are said to do better then the Missouri bullets at .309.
I'm shooting a 1-7" and have better luck with 180-200 gr bullets.

45 for me · Jul 16, 2016

I am going to check the barrel for lead fouling too. Do you think hot barrel & lead bullet combo could cause this? The weird thing is they seemed to be stable with slow fire.

Thanks for the tip on Leatherhead.

Twodogs · Jul 17, 2016

Wouldn't hurt to give the barrel a real good cleaning and shoot some slow 3 shot groups.

Camelfilter · Jul 17, 2016

?Polymer melting/melting too soon under rapid?

PaulB47 · Jul 20, 2016

Verify your velocity after getting things heated up? Should be the same but who knows...

I agree too with looking at a larger diameter. Maybe harder too?