If the extractor looks OK and the brass are trim to the proper length, then the only thing I can think of is the thickness and the diameter of the rim. thier size vary from bactch to batch and makes. Are you guys using mixed brass?

From my experience, I prefer Win. brass they seems to be thicker compare with Rem. Fed. OK too, but the FTE I've also experienced mostly are from using Rem. brass, this problem largly goes away once I stick to using one batch of Win. brass.

Around here, I can't get Rem. 148 gr. HBWC, dealers just don't stock them, so I mostly shoot Hornady 148 gr. HBWC which are easier to get, I've load 3.0 gr. BE with them without problem, usually I'd load 2.8 gr. BE or 3.2 gr. W 231. works well in my 52-2.

Tony