I bought a rifle very similar to yours, with a crummy 357 Mag chamber. Cut the chamber to 357 Max and it now shoots well. Here are a bunch of results I have developed, all at 100 yards and under 2" MOA:
125gr,FR-Berry's, 24g IMR4198
140gr, FTX, 16.5g 2400 (best group)
158gr, RN-Berry's, 24.6g IMR4198
158gr, RN-Berry's, 16.2g A2400
158gr, RN-Berry's, 26.9g IMR3031
158gr, XTP, 26.9g CFE BLK
158gr, XTP, 14.5g A2400 (357 Magnum cartridge)
180gr, XTP, 14.3g A2400
180gr, XTP, 17.2g IMR4227
180gr, RN/FP-GC (Quality Bullets), 17.7g A2400
180gr, RN/FP-GC (Quality Bullets), 25.7g IMR4198
180gr, RN/FP-GC (Quality Bullets), 20.7g IMR4227
180gr, RN/FP-GC (Quality Bullets), 16.6g LilGun
Check the Shooters Reference site to get comfortable:
(You need to Login or Register to view media files and links) Good luck - a great single shot round paired with a great rifle.