Barrel Measurement.

R

Rustystud

New member
I chamber a few barrels and most manufactures write or stamp the bore and rifling IDs on the barrel. I have both pin gauges +/0/-.0002 and reamer pilots in .0001 increments. The problem I am encountering the diameters written and stamped are not what I am finding. I clean the bore with a nylon brush to insure no lapping compound is in the bore. I realize temeprature coul be the difference. I measure my barrels at 68-72 degrees farenheight.

Most measurments are with in .0004 to .0006. I am wondering if I am measuring incorrectly or are the barrel makers and/or tool makers measuring incorrectly. When I check the pins or pilots they measure what is indicated by the manufacture.

I have found the bore size marking inconcistency accross the board with different barrel makers.

Have any of you found this to be true with the barrels you are buying?

Nat Lambeth
 
one of my dashers john said he used a .2365, the latest .2360. both kriegers, both ordered and stamped .237... they shoot great so i don't care, but it is intersting.
tom
 
Are you measuring near the ends, or after you cut the ends off to get rid of what I've been told is a larger diameter due the lap?

Are they consistantly larger? Or is it pretty much equal +/-?

Fitch
 
The maker will remain un-named, but a good number of 30 caliber barrels were all marked .3080/.3000. And they weren't. Are they just marking what looks right?
 
One thing I can think of is you won't be able to put a .2688" pin or bushing in a .2688" hole. That is a press fit I think. The last couple barrels I have put reamer bushings in were also a little larger than they are stamped. I wouldn't think that the instruments used are that different either. I check mine with standards very often.

Joe Hynes
 
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