My Speer manual shows WIN 296. Min load of 25.5g @ 1562fps, and max load of 27.5f @ 1664 fps. I have shot this and it is a powerful round. That bullet will penetrate a heavy car frame with full expansion, and will still expand in a 3" roast. I know, I did it. Hold on tight though.
From the Speer manual, I like using Unique, min 10.5 @ 1212fps, and max 12.5 @ 1392 fps., with that same bullet.
Also, from Alliant website, I like the Laser Cast .430-240g SWC, 7.0g Unique, primers, LP, @ 899 pfs. This is a fun round for sending down range. Recoil is miniml IMO and it is not a powder hog. It is deadly accurate at 100 yards.
Nice caliber you have there. Pics of the gun???