I had great results with RL-17 in a 260AI. 2980 FPS, 142SMK, with 44.2 gr of RL17. No pressure either.
I had it up around 3050 with 44.8 gr, but that started showing pressure signs.
The temp sensitivity was very real. I did the load development in Oct in 60 degree weather. 2980 fps. Same load...