New Ruger Bisley keyholing

[Skipper]

Just got a new Lipsey's Ruger Bisley in 44 special. I slugged the bore and came up with .430".
I shot it yesterday using the Keith 250 gn, lyman #2 alloy, sized .431, tumble lubed, over 12 gns of 2400.
About 50% of the slugs keyholed at 10 yards. Anyone else encounter this problem?

[KCSO]

Measure the chamber mouths I'll bet they are small 429 or so.

[RobS]

Yep sounds like the cylinder throats could be sizing down the boolit upon exiting the cylinder. The slugged bullet from the barrel should pass through each cylinder throat and ideally with a just the slightest amount of resistance. It is ok if the slug moves through with no resistance as long as it isn't too extreme with grossly oversized cylinder throats in most situations.

If your slug fits the cylinder throats the next thing I would do is pull a boolit from a loaded case and measure it to make sure it is still at .431". Sometimes a person sizes to a particular diameter and in the reloading process the boolit becomes swagged down to a smaller diameter.

[Skipper]

I'll slug and mike the cylinder...that's the one thing I didn't do.
Thanks! :Fire:

[runfiverun]

especially if it's stainless.
I got a pair of the standard and a bisley in 44 special.
[still haven't shot the Bisley]

the stainless has a couple of small throats.
just switching the cylinder from the blued to the stainless revolver shrank groups by 75%.
I need to send the cylinder to Doug-guy.

[fredj338]

especially if it's stainless.
I got a pair of the standard and a bisley in 44 special.
[still haven't shot the Bisley]

the stainless has a couple of small throats.
just switching the cylinder from the blued to the stainless revolver shrank groups by 75%.
I need to send the cylinder to Doug-guy.
Likely the cyl throats are small, a classic Ruber problem. So the bullets are getting swaged down, maybe as much as 0.002", Yes that will bugger your accuracy, cause leading too. I use pin gages, but forcing a soft lead bullet thru each, measure, that will do. I have a RBH 45colt that had 0.450" throats, it didn't keyhole, but leaded pretty badly in the first 2". After I opened them up, leading went away & accuracy was about 100% better.

[telebasher]

My throats were fine, but had constriction in barrel at the threads. Lapped that out and she shoots like a dream with .430 boolits. Tap a soft lead ball in from muzzle to see if you have some thread pinch. It doesn't take much to get things out of whack but it doesn't take much to fix either.