5 vs. 6 shot strength

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gnappi

Blackhawk
Joined
Jul 4, 2023
Messages
591
Location
Florida
Given identical width cylinders, I know the cut in the cylinder for the latch in a six round cylinder makes it "weaker" by virtue of the cut being over a cylinder as compared to the same gun would be with a five shot cylinder with its cut being between cylinders. Has anyone ever done destructive testing and evaluated the actual bursting strength differences between the two?
 
Joined
Dec 8, 2005
Messages
4,514
Location
Lemont, PA, USA 16851
I don't think it really matters where the notch is cut, when the round is fired the pressure does go outward in the case for a very brief time but then dissipates (microseconds/miliseconds) as the bullet travels out of the case and cylinder and down the barrel. My questions would be, has anyone even seen a picture of a cylinder that has failed at the locking notches. I would think that if someone had one fail there the picture would have been published and the facts as to why would have been told.
 
Joined
Dec 2, 2017
Messages
190
Knowing the liability issues, I have read that the manufacturers look for a strength rating around 40% higher than the normal demand placed by each caliber. They like to measure their strength ratings at the thinnest spots, not on an untouched cylinder blank. As you can guess, that will vary wildly among different guns. Having said that, I blew up a .41 Blackhawk with an handload (double powder charge) and it split the full length of the cylinder. I doubt that any milling would have altered that location very much. It focued on the area directly above the cartridge. It bulged the backstrap of the gun, and the backstrap surely limited the extent of spread at the cylinder.
 

anachronism

Single-Sixer
Joined
Sep 20, 2008
Messages
402
Location
Lincoln, NE
Here's a nice article by Ross Seyfried on 5 shot revolver that may help you out with at least some information. FWIW, not all revolvers have the locking notches directly over the thinnest part of the cylinder. My Redhawk for example has the locking notches at least 1/4 inch offset from the thinnest part of the cylinder wall.
https://www.docdroid.net/udfr/july-1990-pdf
 

gunzo

Hunter
Joined
Sep 8, 2010
Messages
2,081
Location
Kentucky
Getting the chamber away from the notch helps, but wall thickness between the chambers might be the biggest advantage for going from a 6 to a 5 shot.

While John Linebaugh didn't pioneer it, he likely tested theories & wrote the most about 5 shot conversions &/or very heavy loads in revolvers. A good search for a cold rainy day would be googling Linebaugh articles. There are many.
 
Joined
Oct 24, 2007
Messages
11,745
Location
Kentucky
Slightly off-topic, Marvin's comments regarding cylinder throats is applicable to totally stock Ruger .45 Blackhawks. I've had all my .45 throats reamed to 0.4525" as I've never had one with proper size from The Factory. The hottest loads I shoot are just barely creeping into the lower end of the "Ruger Only" range as I'm not into the hot stuff. Can't say I see any noticeable difference in recoil, but I do see better accuracy consistency, and leading is essentially gone. The eleven degree forcing cone reaming helps here, too.

For what it's worth, I was surprised to find factory cylinder throats at 0.447" as Marvin mentions, and it was pretty common to find all six chambers had different throat sizing. Uniformity can't help but be an improvement. :D
 
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