Lots of interesting options, all. I'm going to start with the 100 grain Hot Cor and Interlock, based on Mule Deer's kind offer.
This is also making me consider chopping a few inches off the barrel to make the rifle handier, given that I don't need to generate high velocity.
Quick range report. I had time for a quick trip to the range and shot at 25 yards to check on what would stabilize. I tried the 100 grain Speer Hot Cors, 100 grain Interlocks (with and without tips filed off), and 100 grain Partitions with the tips filed off. Each bullet over 47.7 grains of Accurate 4350.
The good news is that there is no evidence of keyholing with any of these bullets and no wild groups in the bunch at that short range. Next step is to sort out which is more accurate at 100 yards.
Thanks again for all the suggestions and especially to Mule Deer for the bullets and load advice.