Proper cylinder gap/end shake measurement method?

[Kevenn]

Hello. I’ve appreciated everyone’s help as I’m still new to this forum. I have a SW Model 29-2 and recently measured its cylinder gap. With the cylinder pushed all the way back I couldn’t get a .007 gauge to insert but a .006 barely slid in. With cylinder pushed all the way forward a .004 barely slid in and a .005 wouldn’t at all. So end shake is exactly .002 with gaps measured at .004 & .006. So my question is that I hear the proper way for gap measurement is with a spent case in the cylinder over the barrel and the trigger pulled all the way back and the hammer down?? Is this correct? If so the gaps would be even tighter but the end shake would technically be the same .002. Any one have thoughts on this? Also it appears that if my measurements are correct I assume it’s within S&W factory specs? Thank you

 

[BC38]

Hello. I’ve appreciated everyone’s help as I’m still new to this forum. I have a SW Model 29-2 and recently measured its cylinder gap. With the cylinder pushed all the way back I couldn’t get a .007 gauge to insert but a .006 barely slid in. With cylinder pushed all the way forward a .004 barely slid in and a .005 wouldn’t at all. So end shake is exactly .002 with gaps measured at .004 & .006. So my question is that I hear the proper way for gap measurement is with a spent case in the cylinder over the barrel and the trigger pulled all the way back and the hammer down?? Is this correct? If so the gaps would be even tighter but the end shake would technically be the same .002. Any one have thoughts on this? Also it appears that if my measurements are correct I assume it’s within S&W factory specs? Thank you

FWIW, I have never measured gap/endshake with a spent cartridge in the cylinder. Never even heard of anyone doing it that way. Putting a spent cartridge in place is the correct way to measure headspace AFAIK, but not for measuring endshake/gap.

But if I'm wrong I'm sure someone with more knowledge will be along shortly to correct me.

 

[22hipower]

I wouldn't know one way or another however I did watch a gunsmith check the gap on my 27-2 after installing a new barrel this week. No cartridge in the chamber, simply used feeler gauges and trimmed the barrel until getting a .004 gap.

Jeff
SWCA #1457

 

[Kevenn]

Yes the method with having a spent shell in the cylinder doesn’t make sense to me either, but it would show true cylinder gap in a real live fire situation. Either way I have heard of many guys only measuring gap size with the hammer down and the trigger fully depressed. Any thoughts to that? Might not make a difference either way!

 

[jcelect]

Measuring?

Measuring anything with the hammer in the fired position gives you no useable information! You are inserting a feeler gauge into the rear of the cylinder and the end of the firing pin! The feeler gauge will push, and move, the hammer back against the main spring pressure.
jcelect