Welcome Fire Fox 357

How many fps, can you push a 145gn swc in .357 befor leading  starts.

With lead bullets there are a lot of variables that go into "leading". Bullet hardness would seem to be the most obvious but bullet match to chamber, forcing cone and barrel are even more critical, then comes powder choice, lube, etc. There is no "hard and fast" velocity number that I'm aware of. In the .357 it can happen at low velocities (say 800 fps) if all the combinations are wrong and I have seen some go as high as the 1,200 fps range with no problem when everything in "just right". I think most loaders stop using PB lead bullets around 1,000-1,100 fps and start moving to Gas checked bullets. If you get leading with gas checks then velocity is not the issue.
One of the reasons I like .40+ cals. I can push them faster with PB bullets without worrying as much. The larger surface area on the base of the bigger bores tends to mitigate leading.

I don't cast for cartridge guns. I used to buy cast bullets at guns shows or small shops on my travels. No more. There is a tremendous difference in quality of cast bullets. I buy all my pistol cast bullets from one place now- Mastercast. I get only very minor leading after a lot of shooting in 38, 357, 45acp, and 45 colt.  I only  live an hour from the factory, and it is a very professional operation.  They are also hunting dog folks, so its fun to go see them as you are sometimes greeted by a pack of beagles. Their 225 Grain 45 FP is a nice bullet for all my 45's. Their 38  DEWC is my practice load with Trail Boss  powder in my little Airweight.

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