Failure to feed-125bt's-M1S SBR

[AlcoholicusMaximus]

I really thought I had it nailed down. M1S 10.5" AR15 in .300 whisper, gas port opened to .086, which cycles 220smk's subsonic flawlessly. Extensive load research led me to produce 300 or so 130gr Speer HPs, pushed by 18gr of W-296, which I have decided to replace with 125 Nos BT's due to too many FTF's with the Speers. Now, the 125's are hanging up, about one in 15 shots, usually the last, or second to last round in the mag, but not always. Both loads are having the same issue, which is that the tips are impacting the barrel outside the chamber at about 11 o'clock, and seems to happen only on the right side of the stack. I am using Magpul 20rd, CProducts 20rd, Bushmaster 10rd as well as Colt, OKAY & others.
I thought the short throat was causing me to seat to 2.107 with the BT's & the 130 Speers right at 2'', but the LC brass is just barely thin enough to jam into the chamber, and I realized that I have almost another .1'' to seat out before contacting the lands. I will test and report. I was getting about 2100fps.

[i8asquirrel]

I had simular problem with W296 went to 4227 and 1680 cured it.

[Ron458]

Sounds like the rounds are getting caught under the ejector. This happens on the right side only. Just put a light bevel on the ejector down toward the 7oclok looking at the face of the bolt. IM me if needed.

[Alleycat]