280 AI and Retumbo

[DC125]

Hello,

I have a 280 AI in a 22” proof barrel. I am shooting 175 gr Berger EH with IMR 8133 at 2800 fps and can no longer find any more powder. Retumbo is as close as I can find on the burn rate chart but am not seeing the speeds I was getting with 8133. I am only at 60.5 gr and seeing no pressure signs but am at book max from what I can find online. I am getting 2650 fps, is that as good as I can get or would you try to squeeze a little more out of it? I would like to atleast get to 2700 fps if possible. All groups were around 1” with some getting down to 1/4” at 100 yds during testing.

Thank you

Dave

 

[NorCal 707]

You might try H4831, Staball 6.5 or if you really want some juice IMR7828, Reloader 23. I shoot the 175 EH at 2968 fps with Rldr 23.

 

[Sinistram]

What about the new StaBall HD? On the burn rate chart it's directly next to 8133. I hear good things.