You have a lot of $$$ in a well-made revolver, myself I'd spend a little time measuring the cylinders/chambers of the cylinders before making a decision on a mold.
Start with putting a piece of 357mag brass in 1 of the chambers of the cylinder. Measure from the top/rim of the brass to the front of the cylinder & write that # down. Take and measure that 357mag case and add the # you wrote down together. This will tell you the max oal of a load that you can use. It also gives you a usable number you can use to ask people who recommended bullets what kind of oal are the getting from them.
While you have the cylinder open you should find out the diameter of each chamber by slugging them. You want them all even along with now you have a # that you can use for sizing your bullets.
The next thing you should look at while the cylinder is out/open is to use the same bullet for testing making sure that bullet is 1/1000th" larger in diameter then the holes in the chambers. Lightly drop the large bullet in each cylinder and measure from the bullets base to the back of the cylinder. You want these #'s to be even or close to even. Add all 6 #'s together and divide by 6. Subtract that # from the 357mag case length. This will tell where the leade's in the chambers are.
A picture of 2 reloads, the top reload has the bullet seated to the mfg's recommended oal. The bottom reload has the bullet seated longer/out further into the leade of the chamber. Diong this aids in aligning the bullet in the chamber and increases accuracy.
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I recommended the Mihec 359-640 bullet, mp molds cast a .359" bullet (8/9bhn with range scrap) that weight +/- 158gr (depending on which hp pin is used) and a 170gr fn bullet that has an upper and lower crimp grove.
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That 359640 bullet loaded in 357mag cases measures 1.610" (crimped in to crimp groove) from the bottom of the cases base to the top of the bullet. The cases base measures +/- .060", the part that does not go into the cylinders. The end result is a reload that's 1.500", in comparison the lyman 358429 crimped over the top drive band to be able to fit in the short cylindered revolver (n-frame and others/check your oal) is 1.553".
Having 2 crimp groves makes a huge difference in the ease of use of this bullet. These reloads are loaded in 38spl cases, the 359640's were sized to .358" and crimped in the bottom lube groove (loaded long). The h&g #50 bb wc was sized to .357" and crimped in the middle lube groove/loaded long. These 38spl reloads loaded long were made to shoot in a 357/designed to get the bullet out into the leade of the chambers of the cylinders.
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Typical 6-shot groups @ 50ft with those reloads pictured above in a 357mag.
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Those groups were shot with iron sights with the revolver rested. The 357mag I shoot the most can be shot with iron sights/reddots or scopes with ease. The integrated rail on the bbl shroud allows the shooter to change over from irons to scopes/dots in seconds,
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Same revolver scopes rested @ 50yds using 2 different fn hp bullets & 5.5gr and 6.0gr loads (2 different bullets/2 different loads). The worst of the 4 groups was 2 3/16" outside to outside measurements.
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Anyway with the $$$ you have invested in that python you might as well feed it the best blammo ammo you can make. I know my 686 does.