I have the same barrel. There are some brands of brass that are too thick for the M1S chambers, for me, it was FNM brass. I think the throats are a little short also, this will require seating the bullet deeper. Brass that is working for me is R.P., older L.C., Winchester, PSD.
I ran some Tubbs Final Finish through mine and it seemed to help with being able to extract unfired rounds.
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