Here's what I dredged up from my Sierra Handgun Manual (4th ed.) and my reloading notes. Sierra used IHMSA cases and Fed 210 primers in a Dan Wesson 8" barreled revolver.
240 gr Sierra JHP:
33.5 gr H110 - 1,600 fps
31.4 gr IMR-4227 - 1,600 fps (accuracy load)
38.9 gr AA1680 - 1,600 fps
250 gr Sierra FPJ:
32.3 gr H110 - 1,550 fps
31.9 gr IMR-4227 - 1,550 fps (accuracy load)
38.7 gr AA1680 - 1,600 fps
300 gr Sierra JFP:
30.4 gr H110 - 1,350 fps
27.5 gr IMR-4227 - 1,300 fps (accuracy load)
33.9 gr AA1680 - 1,400 fps
My load info (wow - it's been 20 yrs since I shot this barrel!) I used starline cases and CCI-200 or Fed 210's. I tried Fed 155's, but finally went with the large rifle primer. I partially FL sized my cases (like you) just a little further than the base of the seated bullet.
265 gr Horny FP:
33.0 gr IMR-4227, SD = 2.075" (well out past the cannelure) This was as high as I went, but no pressure signs indicated in my notes.
300 gr Sierra JFP:
30.0 gr IMR-4227. Again, no pressure signs indicated in my notes.
Use my data at your own risk, but you've got a very strong action and I was not worried about going higher than Sierra's loads, especially when I was seating those longer bullets out past the cannelure.
