barrel micrometer

[jona710]

Telescoping gauges are pretty slick. Use them in the aviation world for close tolerance measurements. With a micrometer of course.

 

[CanAm]

easiest way is to slug it. But only decent way to check along the bore is an air gage

 

[buckbrush]

easiest way is to slug it. But only decent way to check along the bore is an air gage

Bingo

 

[peterdobson]

Thanks- informative technical comments and also some business advice - appreciated. We have been mainly an ammunition company but have expanded into barrels and this has been a learning process.

Best regards,

Peter

 

[guntech]

I would leave the barrel measuring up to the manufacturer. It doesn't take long for a barrel maker to get a reputation one way or another...

 

[Duck_Hunter]

Did the gunsmith mention how he determined the bore is oversized?

 

[marshman]

If the bore is tight but the lands are shallow by say .000? Is it over or under? Pin gauges will just confuse you

 

[peterdobson]

He did not mention how the bore was oversize. We are having John Marshall check.

 

[Leeper]

Peter,
One can check diameter with a lead slug but there are limitations. For instance, if there is a loose spot in the middle of the barrel, it is impossible to measure it with a slug or with gauge pins. I spoke with a fellow in Arizona who has one of the old Springfield star gauges but says the use of it is a bit of an art in itself.
Generally speaking, a lead slug and micrometer will tell one all he needs to know except as noted above.

 

[peterdobson]

Thanks guntech, Leeper. Marshman, CanAm and all.

Peter

 

[AP]

Did the gunsmith mention how he determined the bore is oversized?

Thats an excellent question - perhaps he decided to ‘lap’ the barrel ... and got a little ‘aggressive’ with some old clover 54 valve compound - and decided to remove and replace the lap a few times to see how he was doing

 

[peterdobson]

John Marshall advises the barrel is exact spec at breech and .001" tighter at muzzle.

 

[guntech]

John Marshall advises the barrel is exact spec at breech and .001" tighter at muzzle.

Keeping in mind probably an inch should be removed from the muzzle of a barrel blank ... slight tightness towards the muzzle is desirable.

 

[peterdobson]

Thanks guntech and that makes sense.

Peter