Well... since i didn't have any problems with the S&B and Fiocchi I loaded up some test rounds using Small Rifle primers. I loaded 10 each of a mid-range load using Wolf SR, Winchester SR, Remington 6 1/2 SR and CCI 400 SR. I figured this would show me for sure if there are any problems with hard primers. I also figured I could chrono them and see if they are any hotter than with regular SP primers.

I tested them today and all except 2 went bang. One Winchester and One Remington have a very light dimple. Surprisingly all of the CCI fired. I know this probably isn't a large enough sample set but it seems to indicate the gun may have intermittent issues.

Also of interest... if any of you read my 'pimply primers' thread, almost every one of them (except the Wolf copper cups) exhibited the same look as I was asking about in that post, so I think they may be related. Looks like this gun will be going back for the 5th time.