25 - 40 whacks to loosen a 425 grain bullet ? That may be as good as it is going to get.
You probably already know this, but here is my list of things that help keep bullets from walking out (but then I don't shoot cannons
-- turn down case mouth belling stem diameter so the stem barely touches the case. All it should do is knock dents out of the case and bell the mouth.
-- use a deep seated design (short nose, long body) if you have a choice in the matter.
-- ordinary roll crimp, and don't overdo it. An excessively "hard" crimp may actually reduce bullet pull because it bulges the case a little.
-- new cases grip better than cases that have been reloaded many times. Old cases can be freshened by annealing the necks (and only the necks) but it's a lot of work.
Can't think of anything else.
With some guns, you just have to reduce the load. My S&W 44 from hell was that way. A full house 280 LFN would unlock the cylinder and
walk bullets out of the case. At the time, I wasn't able to solve those problems, so I downloaded it to 1100 fps. The 1100 fps load put a lot of meat in the freezer.
Can't say that I've ever had a problem with a 357 walking bullets out of the case.
As I get older, I appreciate the humble 357 more and more. It's easy to load, easy to shoot, and easy on the wallet,
But if everyone shot 357's, I wouldn't sell many molds, would I ?