Python barrel bore dimensions....

[philthephlier]

Is .355" groove diameter normal for a Python barrel?

[Urny]

In my experience, yes.

[philthephlier]

What would you size castboolits to with that groove diameter?

[winelover]

I size mine to .357, for my Python.

Winelover

[GabbyM]

Size To a tight fit in the cylinder throat.

[cbrick]

Actually size to a mild snug fit in the throats. The purpose of the throats is to guide the boolit aligned with the center line of the bore. The purpose of the throats is not boolit sizers, they may be the worlds best boolit sizers but the less the boolits are molested the more accurate the revolver.

Rick

[KCSO]

All the Pythons'i have worked with were 355-356. That and the twist is why they were thought to be more accurate thwn the Smith barrels.

[Char-Gar]

Yes.... .355 sounds about right. I would shoot .358 cast bullets. If your Python runs true to type, the cylinder throats will be .358 or a smidge larger.

[cbrick]

winelover just stopped by here with his Colt 357 & some un-sized NOE 180 gr boolits cast at just over .360". I used the pin gauges on his throats and all were pretty uniform at .359" with the pin gauge very slightly loose so maybe .3592-3". He doesn't have a .359" sizing die so I sized a couple with a .359" Star die (came out .3587") and they are just a near perfect fit.

He is now off to try & find a RCBS Cowboy expander plug (mine is .357") and a .359" RCBS sizer die.

We didn't slug his bore but I would bet it's under the .359" so he is good to go and a happy camper.

Rick

[felix]

I have two Pythons, several years apart in manufacture. Both have cylinder openings of 360, and grooves of 354 at muzzle. The barrels are choked, and I would say severely. Twist at 14, both guns. More accurate than the typical 19 twist Smiths? Not with medium to hot loads. Rugers are at 16 twist, and their (my guns) accuracy depends almost entirely on the bolt holding power during firing. ... felix

[Char-Gar]

I have about five or six old Colt DA in 38 Spl or .357 Mag.. They all have bores that run .354 - .355 in the groove and cylinder that are on the average .359. I have had a couple of Pythons on the years that run about the same. I have never been that impressed with the Pythons and their mystic. I have not found them to be superior in any way to other Colts of the same period, save the high polish finish (Royal Blue) and the vent rib barrel.

I long ago decided to size all 38/357 bullets .358 and be done with it. They work just fine in all Smith, Colt and Ruger firearms I have tried, which has been quite a few.

This is my current favorite old Colt DA, a 1956 Trooper with gin-u-wine Roper stocks. Caliber is 38 Special naturally. For the .357 Mag round, I prefer the N frame Smith.

[Groo]

Groo here
The older pythons [don't know about the new ones] have a "choked" or tapered bore.
Most ending with .355 to .354.
An old trick was to load 9mm jacketed soft points in a python for light weight SD bullets.

[felix]

Tapered grooves too! ... felix