oilcan72 wrote: ... I have some IMR 4198 and I'm looking to load some Barnes 275 gr anyone have a good starting point?? I'm having a hard time finding much load data, or powder for that matter. I've been using some IMR 4227 and having some decent results, just looking to up my game a little for white tail season. ...
oilcan72-
Wecome to the 450b site!
As far as I am aware, there are only three sources of loading data published by reputable labs: the last couple of Hornady Handbooks, the Western Powders manual, and the recent AR reloading manual from Lyman. Unfortunately, none of these have published loads for the 275-grain Barnes bullet. Also, none of these sources include loads using IMR-4198 for any bullet of any weight.
It looks to me as if IMR-4198 is too slow for use in most 450b applications. Extrapolating from 460 S&W loading information, that powder may have some limited use when bullet weight exceeds 300 grains. If I'm correct in my guess, then trying IMR-4198 with your 275-grain Barnes bullets is likely to be frustrating in trying to improve on your results with IMR-4227. You are likely to find velocities much lower than acceptable, find the cases sooted as an indication of low pressure, and experience problems with ignition, including unburned powder.
If you're getting OK results with IMR-4227, it might be well to go deer hunting with loads using that powder.
Should you try any experiments with IMR-4198 then posting your results, even if they're poor, would be helpful to the rest of us.
Good luck.
--Bob