Help needed for .357 oversize bore

[Quiet Burp]

Guys, I think I might be in need of a bit of advice. I just took my new ( to me ) .357 browning lever to the range for a spot of bragging but the best I could do was 2'' groups at 25yards. After I slunk away, I slugged the barrel and got between .357 and .358. I then miked the slugs that were store bought moly coated jobs and got .357. Now am I right in assuming that the projectile I need is at least .358? Or should it be even larger?Now, is there a mold available in this size? I could be hallucinating here, but I think I read something about sizing projectiles UP... is that possible? Your advice would be much appreciated.

[Leftoverdj]

Bumping bullets up is possible, but not practical, imho.

With rare exceptions, the moulds sold for .38/.357 cast .358 or bigger, often quite a bit bigger.

First thing to try is shooting the bullets you have. They may work fine. If they are inaccurate or lead your bore, you need to try bigger bullets. If you want to buy them, we have custom casters on this board who will set you right up.

Me, I'd buy a  Lee six cavity mold and go to casting.  I bought a 356-153-2R on closeout last month that drops in the .358-9 range w WW metal. If I needed them bigger, I could get another thou or two by adding some antimony to my alloy. No need to do anything more to them than cast, inspect, and lube with Liquid Alox.

[Quiet Burp]

Thanks for your reply, Leftoverdj. I think I might try the antimony trick. Could you tell me how much to use and where to get it from? ( keeping in mind I'm not in the U.S.) Do you buy it in pure form or is it in an alloy with lead or tin?