Well, further to all the recommendations for RL-19, I bought a canister and loaded some.

The RL-19 performance was nowhere close to what I got with N560 and 250 grain SGK.

I was fairly disappointed with the results, although this may be my own fault, at least in part. I tested 3 different loads from 72 to 74 grains , leaving about one minute between shots. The gun might have shot better, had I let it cool down more between shots, as it was a hot day.