I'm going to give this a try in my 28" 260 barrel. I suspect the extra length may provide some benefit with the slower burn rate.
I recall that I had excellent accuracy with the .260 in my factory savage 24" barrel using H4831SC, with some velocity loss. I suspect it will do something similar with the 28" barrel. Added to the higher altitude here, maybe some of the velocity loss will be regained out at the target. Maybe...
Surprisingly, this might also be helpful with subsonics, where a full case with a lower velocity might be less of a problem. Might...
Greg
12/29/22 ETA: I did some more digging, and got a bit of "somewhat" useful info on this Ramshot LRT Propellant. It's pretty slow, but not the slowest, being just a bit slower than the H-4831. I expect to lose some velocity potential, but very time I've done that with my 260's, accuracy tightened right up, with a velocity tradeoff. With H-4350 and 140/142's the 28" barrel had been delivering 2850fps. My 24" 260 was shooting very tight with H-4831, and I have hopes. Given the higher altitude and the 4" of added barrel length, I think I might get a smile or two out of this experiment. I'm expecting to run out of case capacity before hitting peaky pressures, and I would like that to mean my barrel's on a vacation cruise. I'll be running this show with 140gr Gold Dots.