Rate of rifleing twist in 38/357 revolvers

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  • Last Post 24 June 2011
[email protected] posted this 05 June 2011

I own a Colt's Official Police in 38 Special, a Smith and Wesson 686 in 357,and a Ruger GP100 In 38 Special. My understanding is the Colt has a 1 in 14 twist, the Smith a 1 in 16, and the Ruger a 1 in 18. all three guns shoot pretty good. 

Why the slow twist in the Ruger? Why the fast twist in the Colt?

All three guns have a different configuration and different usages so accuraccy comparisons aren't really a fair evaluation of the potential accuracy of the twist.  

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william iorg posted this 05 June 2011

The best - short - explanation of the difference between the three makes and their twist rates was in the Fouling Shot No. 203, January/February 2010 on page 16. The article is “.38 Target Revolver Choices.”

Slim

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Ed Harris posted this 06 June 2011

You are correct that Colt is one turn in 14,” because that's what their old tooling was and it's always been that way...  The Colts give the best accuracy with wadcutters and 158-gr. lead. 

Ruger single-action .357s are 16” and button rifled, because that is what the standard twist is on .35 cal. rifle bores from the people who grind the button rifling heads, and they bought the buttoned blanks from various makers and that's what was available.

Ruger double-action .38 / .357s, Security Six, Police Service Six, Speed Six, GP100 and SP101 are 18-3/4” twist, as are S&W.  Reason Ruger went with 18-3/4 inch twist on the DAs is because this is the pitch on the rifling broach cutters and there is only one company that makes them.  The 18-3/4 twist gives better accuracy with the lighter +P jacketed loads, 110-125 grain. which most people shoot.  For good 50-yard grouping with wadcutters you may need to drive bullets a bit faster than factory to maintain stability.

73 de KE4SKY In Home Mix We Trust From the Home of Ed's Red in "Almost Heaven" West Virginia

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[email protected] posted this 07 June 2011

It would be interesting to know the reason Colt chose the 14 inch twist 100+ years ago. They most have known something cause my old OP does shoot, handling everything from 100 gr waddcutters to 180 gr. beasts and everything in between. The Ruger likes 158gr+p the best. 125s shoot way to low to be practicle and it won't shoot 180s at all no matter how hot I make em. I've only ever shot 125's double action in competition in the Smith so I can't really judge it. It is very competative.All in all the Colt is the most versatile.

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Ed Harris posted this 08 June 2011

I was told by the late Joe Wallace, a Colt armourer who built the Official Police, Officer's Model and Python, that Colt had engineering students at the University of Connecticutt conduct yaw card and spark shadowgraph studies of the .38 Special revolver firing 158-gr. lead RN bullet using the most advanced technology then available, about 1900, to determine the best possible rate of twist for the “new” smokeless powder ammunition. UConn recommended the 14 inch twist of rifling and Colt had their tooling made that way.

I cannot validate the veracity of this story, as when at Ruger I attempted to locate the original reports in the UConn museum archives and it could not be found. If it exists at Colt, it is kept as a trade secret and not talked about, but it is known that when Colt was financially solvent in pre-war days, they were a big contributor to the engineering school, so the account makes sense.

73 de KE4SKY In Home Mix We Trust From the Home of Ed's Red in "Almost Heaven" West Virginia

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[email protected] posted this 17 June 2011

Sounds believable to me

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fRANK46 posted this 20 June 2011

Thanks for posting the rifling twists of Colt, S&W, and Ruger. I picked up a Douglas bbl blank sometime ago and stamped on the breech end is 1x14 38 special. Another project for when and if I ever get the money. Thanks again, Frank

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Ed Harris posted this 22 June 2011

Jim Clark used 14 inch twist Douglas barrels in building his .38 Special PPC revolvers and every one I ever saw was a nail driver.

73 de KE4SKY In Home Mix We Trust From the Home of Ed's Red in "Almost Heaven" West Virginia

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william iorg posted this 22 June 2011

For the new Riger 77/357 Ruger went with a 1-16” twist.

Slim

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tturner53 posted this 23 June 2011

I have just tried my first PPC match. Tied for last. (With a 9mm auto). Now I'm breaking out my old S&W M19 6". Working on 4 loads, two powders, two bullets. The very old Ideal #358432 161 gr wc and Lee 140 swc, I'll see which one groups best using light Bullseye and 4756 charges. I started loading real light, maybe I need to goose it a bit to accomadate the very slow twist? My loads (not tried yet) are 3 gr. BE and 6 gr SR 4756 in .357 brass with each bullet.

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[email protected] posted this 24 June 2011

Now, getting back to the 18 3/4 twist in the 4” 38 special Ruger,and changing the subject a little, what powder would, theoreticly, be best, a fast, medium, or slow?

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