I just received some 275gn .454 slugs from Dry Creek, but havn't seen load data for 275gn. I was thinking of 22gn of H110 as a starter load. Also thinking of trying 2400. This is in a Blackhawk. Would appreciate any wisdom regarding this load. Thanks.

For reasons completely unknown to me, Hodgdon does not list a load for the 275 grain bullet and H110. For the 300 grain bullet, they list a starting load of 21.5 grains of H110, and a max load of 22.5 grains.

I would expect your 22.0 grains starting load to be right on the money.

You might also want to try a starting load of 18.0 grains of Li'l Gun -- this powder does nice things in my .45 Ruger Blackhawk.

I've found that 20 grains of H110 in a Colt Anaconda does nicely, with a 300 grain Saeco. Recoil etc. is mild. I also use this same load in my Rossi mod. 92 with outstanding results.
Jim