While the site was down, I searched the interwebs for any suggestions of using the 250gn Barnes Casull bullet in 45colt +p loads but couldn't find any references, hence a quick write up here so others don't have to waste powder and bullets.

I wanted to use a newly acquired 45 colt RH for deer, but the 225gn Barnes bullet of choice was unavailable, but I had a good stock of the 250gn Casull bullets. Through a lot of Quickload (this load, and other loads shot in the same pistol for calibration) and a variety of 45 colt +p recipes, I worked up a ramp of H110 loading. Chrono data was 50fps slower than Quick load projections, which left me with a functional (terminal velocity limited) range of ~75 yards and poor accuracy to boot. I never finished the ramp and pulled the last load. I have the SRH 454 with me in the field this year instead.

You could have up'ed the load in the SRH 45 Colt until you got the desired results. SRH can stand the pressure same as it does in 454

Yep, that would have worked, but I already had a load worked up for the 454 that shot well. I had found that the RH shot very well for me out to 40 yards and was a little more compact platform and wanted to give it a try.

I haven't tried a 250 gr Barnes in a 45 Colt case but I have used them in the 454 Casull. Very accurate at 25, but some have indicated they rapidly lose accuracy once you go further out. Given how long they are compared to a lead projectile, I wonder if there is enough room in a 45 Colt case to load them up to a high velocity.

I had acceptable accuracy (2" group) at 50 yards with the 454 and a light load of H110 (from the reloading library on the site when the pistol was scoped). As for space, I don't remember the details, but I think I ran out of pressure before I ran out of space and really liked the idea of keeping all my fingers.