Had a buddy with a Brown Whelen way back in the 70's. He ran the 275 Hornady in it, thumped a few elk. Sold it to another buddy who kept it to his death. The steps above are good advice on necking up whatever brass you have then put the BW neck on it just enough to get a solid hold. Load up normal Whelen loads and fireform. Most of the gains from the standard Whelen and the AI or BW are really pressure differences in the handloads I would say. Loading to 60 PSI in the standard whelen with good modern powders will get you to over 2600 FPS in normal barrels with a 250 cup and core.
