Doc, I have not used RL15 in the .257 Roberts. But from what I have used, I'm guessing you'll find RL15 to be a tad on the fast side for heavier bullets. I get good results with 120 grs bullets using VV N160 - which probably falls somewhere between IMR4350 and IMR4831 (just for comparison). That leads me to believe RL15 might be tad fast for optimal velocity. Which of course is not to say you can't get good results accuracy wise useing RL15...

- mike

Can't find my Reliant data at the moment but you should dig it up if you can. At the top end of the bullet weight range RX19 and 22 will generate excellent velocity. RX15 rules the roost for Bob with the light weight bullets IMO.

Thanks for the link Steve...nice website