how do you calculate a barerels given thickness,,or can we do formula?

[long rifle]

i have a barrel and would like to know how thick is this? so its a .40 rayl barrel brandie new! what I like to know is there a foumula i can use to figure this?I have been using the barrel size .750 and just dividing the thing in half,Does this work? mickey

[Jerry V Lape]

Barrel dimension across the flats (.750) minus bore diameter (.40) minus 2 times the depth of the grooves, then divide that number by 2 and you will be close to the wall thickness of the barrel at the place you measured it across the flats.   Just because the bore is supposed to be .40cal doesn't mean bore is exactly .40".  It may be under or over that size.  And determining the groove depth isn't particularly easy unless you slug the bore with a piece of lead to get the real measurements. 

[Dogshirt]

Just mic it at the bottom of the groove. Plain and simple?  Ain't no need to make it any harder than it is.

[billd]

To find wall thickness subtract the bore size from the outside diameter across the flats and divide by two.  That will put you real close.  If you know the rifling depth subtract that from the final answer.   That will be the exact measurement.  Bill

[Dphariss]

 Bore size + depth of grooves so a 40 is going to be a .420-.425 in most cases.
Subtract this from the exterior dimension then divide by 2.
.420" - 1" / 2 = .29
Dan

[Acer Saccharum]

Also you gotta consider for the bore being off center a touch. Nothing is ever perfect. But the only way to tell for sure is to cut the barrel in half and measure the wall with calipers. 

[huntinguy]

Ultrasonic micrometer. Just have to have a known to set it to,  might have to make sure your not on the land though.  just watch for the change in thickness and you will know if land or groove.

That is if you must know that close