Not wishing to teach Grannie how to suck eggs, but RL15 might be just a touch quick as a choice of powder.

A little play on QL, without any burn adjustment, throw up the following data... and lists max. pressure at 40611 psi.

RL15 x 67g/2175mv/41654psi 81% fill
RL17 x 71.5g/2202mv/40414psi 83% fill
RL19 x 78g/2192mv/40033psi 95% fill
RL 22 x 82.6g/2238mv/40069psi 99% fill
RL25 x 82g/2149mv/34502psi 100% fill

N560 x 73g/2184mv/37940psi 86% fill

RL22 looking the most promising.