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Discussion Starter #1
First of all I want to thank Iowegan again for the IBOK on the GP100.
The revolver involved is a GP100 161, Blued 6” barrel.
After checking some clearance tolerances with a feeler gauge, I recorded the following:

Barrel to Cylinder Gap .005”
End Shake 0

Head Space .004”

I have never had a problem with cylinder drag but am I in for it in the future?
If this cylinder is too tight both front and back, there is not a lot I can do, correct?
I know I can chamfer the crown to the point of actually sharpening the cone and I know that is not the proper thing to do.
I have never seen a problem with a (clean) revolver being too tight, so this is very unusual to me.

Probably the most rounds I have ever shot in this gun at one time without cleaning is 100 +/- when I changed sights. No problems found at that time. Or at all.
 

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Drummer, Are you absolutely sure you measured headspace properly? Make sure you use a virgin brass ... no primer .... brand name brass such as Federal, W-W or R-P. The thickest feeler gauge (gap gauge) that will fit between the recoil shield (firing pin hole) and the case head will be headspace.

Make sure the firing pin hole has not been peened forward (from dry firing) to make a high spot. Make sure the blade(s) on your gap gauge do not have burred edges (very common).

Nearly all GP-100s are going to measure between .008 and .012", with .010" as optimum. .004" headspace will work but there is no room for high primers or any accumulated powder crud.
 

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Discussion Starter #3
I have no virgins anywhere around here. I used a spent casing and smack my hand a live round. Would that make that much difference? And the feeler gauge is brand new, just out of the package and a high dollar Craftsman brand.
The recoil plate is flush enough to make it seem one piece of metal.
 
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