Update.

by Hoot , Diversityville, Liberal-sota, Monday, July 25, 2016, 15:31 (3046 days ago) @ Hoot

Had 3 different loads on hand and tried them all out this weekend. The original load described above (5.0 Unique, 158SWC, Fed 100), 4.8gr Unique under 160gr SWC w/Federal 100's and 3.2gr Bullseye under 158gr SWC w/CCI 500's (loaded lite for pistol league use). We shot them out of the USFA, a ca. 1933 S&W M&P (M-1906?) (yep, not rated for +P and I don't normally use them) and a Taurus M-85.

The USFA cratered the Federal primers on both loads but not on the CCI's. The S&W (chosen due to the hammer mounted firing pin) one could just see kind of an 'eyebrow' over the primer indent on the Federals and none on the CCI's but did not exhibit any sort of hang-up during cocking. The Taurus (frame mounted FP) had no issues with any of the above.

I pulled the cylinder on the USFA and looked under full daylight and there is a bit of a gap between the FP and the bushing. It isn't symmetrical though and appears to be from say, 7-o'clock to 9-o'clock. The remainder of the circumference looks pretty snug. The FP looks exactly like the conical one shown in Jared's post.

Firing pin indents from the USFA also seem to be very significant no matter which primers are examined. They are being dealt a might whack all right.

Short term, I'll avoid Federal primers. Mid-term, try and get a measurement on FP protrusion and see if there's any trouble there. Longer term, keep an eye on the bushing to see if anything changes.

Thanks for all the good thoughts!