Casting for a Python

Bishopus

Bishopus

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So I just slugged the bore of my 6" python and discovered what is probably old news to the old timers--these bores are tight! I slugged it twice thinking the first was some sort of fluke, but nope: it measures out at .356, tops. Maybe closer to .355...

My question is, what's the right size for a cast bullet through this bore? I'm assuming .356, but would love to hear from other Python shooters who have gone down this road with cast bullets.
 
Sounds tight to me but have never owned a python, all you can do is try some diff. dia's. and check for leading and accuracy. M.T. Chambers makes some heavy duty .357 bullets including Keith type gas check bullets in .355",.356",.358", and .359", to match some of these dif. barrels.
 
They are tight (I currently have one, and have owned a couple of others in the past). They also have a tapered bore, that is, they are slightly tighter at the bore end then at the chamber end. If using soft cast, keep velocities down and 358 bullets will work fine. If hard cast, try and find 356-357 (or make your own) bullets. - dan
 
Bishopus: Lino is probably harder than necessary for your purpose. Plus it is darned expensive. I would use it sparingly with either wheel weights or lead.
Now that you have checked your bore diameter also check your cylinder throats. Ideally they should be a bit larger than the bore. Between .001 and .002 is ideal. A lot of revolvers aren't so set up although you would hope Colt did so for their top of the line gun.. The idea is not to swage down the bullet as it leaves the cylinder and then end up undersize when it gets to the bore. If this happens with a very hard bullet you will likely have more lead problems than with a softer one as you are unlikely to get any bullet upset to fill the bore.
 
I have one, a 6" model, four diget serial # 2***, supposedly made in the first year of production. Compared to the later varieties, there are a few slight differences, the top of the front sight is flat, configuration of the rear sight was changed, grips are fully checkered and the bore apparently is tapered. 0.356" sized bullets work well in mine but something else you may want to check is diameter of the mouth of the chambers in the cylinder.
 
I sized a bunch of 158-grainers down to .356 and tried 'em out today. Accuracy is definitely there! I'm getting 1.5" at 25 meters, lots of holes touching. Very little leading.

I used straight lino again for this batch (as per Lyman...) but agree that I could probably go softer; I'll mix up some 50/50 lead/lino and see what kind of results I get.
 
Boomer said:
Never mind the bore diameter, measure the throat diameter of the chambers and cast to match that diameter. Accuracy will suffer otherwise, regardless of how tight the bore is.
Click to expand...
The throat diameter is something that should be checked and is definately a consideration for sized lead bullets. I've found the throat diameter 'usually' to be a few thou greater than the bore diameter. The closest is actually my 500 S&W and that throat dimension is 0.001" over bore diameter, which is what the cast bullets I use in it are sized to. So, roughly what I've found to work best for me is 0.001" over bore for 357, 0.0015" over for 44 & 45 cal.
 
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