Very good info here.
I've had some similar resistance using a 150gn Sierra bullet, S&B brass case, federal large rifle primer in an M48A. Not often as I used the same 20 brass casings and a local gunsmith/merchant suggested the brass casing as well. Since it only happened twice in a 2 round trip to the range he suggested that it could have been the casing neck wasn't the right dimensions.
Thank you for posting your results here, time to take some notes and do some more testing/checking.
I'm not saying the situation is the same but I checked my binder, I use 3.010" OAL.
thanks for poppin in, i have indeed learned a lot these past few days...thanks to the members on this forum.
have you checked our actual COL per bullet?