Hi. I have a 300 blackout AR that I built. (Build is a Spikes upper/ lower, Geissele SSA-E, noveske barrel, Spikes BCG, and GemTech GMT-300.).  Having had experience with Nosler ammo on other platforms I ordered 110gr BTs and 220gr match grade ammunition from shooterproshop. Once I got to the range, the 110 gr Nosler Ballistic Tips and 220gr federal armament ammo fired without issue. I immediately had issues with the 220gr nosler ammunition failing to fire though. Trigger went forward—and nothing but click. When I ejected the round, there was no indent on the primer—and the charging handle was difficult to pull back, like the round was stuck. I tried several rounds from several different boxes and had the same issue—it appeared the firing pin was not striking the round. Some rounds would go off—but 90% of them did not. And there was no indication of the primer being struck.

To troubleshoot, first thing I did was change out the firing pin. I fired over 100 rounds of 110gr BTs and 220gr federals with no issue, and first round of the 220g Custom Comp Noslers failed to go off—with no appearance of primer strike. Next, I thought it may be the trigger—so I switched out the trigger springs and headed back to the range. I ran into the same issue—failing to strike the 220gr nosler ammo. Next, I put the 300 Blackout upper on a different lower. Even with the different lower, the majority of the 220gr noslers were not going off with no appearance of primer strike. To make sure it was not the lower that was the issue—I put a 5.56 upper on the another lower and fired 200+ rounds with no issue.

I think the 220gr Nosler ammo is sitting too far forward for the firing pin to strike.  Has anyone seen or heard of this issue before? Do you have any recommendations for me to fix it?  I’d appreciate any help you can give me.

I called and emailed shooter pro shop, but have not gotten a response.

I've gone through about 200 rounds of that load no issue. Yours is a very interesting issue that i cannot see how it could happen. Did you measure the rounds?