300blkout in my SBR

[my82cam]

So, I finally got my stamps back for my SBR and my Phantom TI suppressor and have started reloading subs for it.  I am shooting a 300blk out of a 10.5 inch SS barrel(pistol gas port).  Using Missouri bullet company 245 cast lead bullets that are coated.  10gr of WC680 puts it around 1030FPS.  The problem is I can not get it to feed the next round.  The bolt stays open on the last round, so, I know it isn't short stroking it.  The flat nose of the bullet seems to get jammed on the top of the chamber.  If I cock it by hand, it will feed just fine, but when fired it doesn't cycle.  Any ideas?

[Photoguy67]

I don't have any experience with those bullets, but they look a bit long. Maybe try a slightly lighter bullet, around 210-220 grain? Those should still stay subsonic.

[Jct1911]

Also what OAL are you using? For some time I used Gordon's 245 design from accurate. It worked in all mags but pmags didn't like to be filled up. The lancers work great, I've also never had issues out of d&h mags with green follower.

[my82cam]

I first had OAL of 2.120, if i remember correctly.  This didn't want to feed out of my bolt gun or my ar15, so, I pushed it in to 2.050ish, and that feeds in my bolt gun and by hand in my ar15.  I am using magpul magazines.  I tried GI mags and another polymer mag when I had the OAL at 2.120 but didn't switch mags once I seated them in farther.  I have a lot of 208 AMAX but I plan on using them for hunting and want the soft lead for expanding purposes.   The AMAXs do not expand well at that slow of a speed.  I know there are high dollar bullets that are heavy that expand very well, but I am trying to find something that I can shoot a lof of and afford to do it.  The missouri bullets are $45 for 250 shipped to my door.  Should I try seating them in even farther?

Edited August 31, 2015 by my82cam

[my82cam]

Thanks for any help, PM sent