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Joined: Nov 2015
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Yes I'm a novice and I'm trying to acquire as much knowledge as I can! I was curious to see if these numbers could be broken down for me, ie what they mean and how it applies to use.

12ga Damascus steel barrel

Right Barrel
.740
.695 wall for
.045

Left barrel
.736 choke
.695
.041

My guess is that (rt barrel) the bore is .740, the choke is .695 and the barrel thickness is .045 and would be safe to shoot just based on minimum wall thickness (.035 general consensus) given all other variables being addressed. Or am I looking at the numbers wrong?

Thanks guys!

Last edited by RARiddell; 06/29/17 08:40 AM.
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You should know the bore diameter, ie: .740, choke diameter or amount of total construction, and minimum wall thickness in each barrel. The important spec is the minimum wall in each barrel, top, bottom side of each barrel. You cannot take the outside diameter and subtract the inside diameter and divide by two to get the wall thickness, you need to measure with a wall gauge.
From the specs you list, I am assuming the left barrel .736 is bore, .695 is choke dia and .054 is wall.
If your numbers are correct, that should be a rather heavy gun.


Dennis Potter
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yep I had the numbers wrongs. The barrels were inspected, measured and given the all safe, I was just curious if I was reading the numbers right. There's a steep learning curve, this I know and I thank you guys for your patience.

Last edited by RARiddell; 06/29/17 08:42 AM.
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one point to add

for minimum wall thickness - the where is important

the walls at the area of the breech/forcing cones are important to know

.054 just before the chokes is a stout gun
but 6 to 9 inches from the breech is too thin

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It is likely that the right bore (and possibly both if the gun is Continental) has been honed, making it even more critical that someone with the interest, equipment and expertise to do so (like Bro. Dennis) has evaluated the barrels; NOT the seller.
If the report does not include MWT at the end of the chambers and the forcing cones (near out eyes) and every inch out to 16" - 18" (near our forward hand), it is inadequate.
I believe Osthaus meant .045" 9" from the breech.
More here
https://docs.google.com/document/d/1ZIo0y746UsSRZIgRuuxwAbZjSBHitO_EanvwLYc-kGA/edit

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yes

kant type

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m-4 Offline
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wouldn't it be .740 O.D. - .695 I.D.= .045 divided by 2 = .0225 wall thickness? Also agree, gauge is a much better way to get accurate measurements. Remember when working with dia. measurements as above you have 2 wall thicknesses in the equation.

m-4

Last edited by m-4; 06/29/17 10:25 AM.
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m-4,
That is true, but the two thicknesses might not be the same, because of being "struck" by hand, and sometimes overly so near the ribs. Unfortunately, it may be hard to get a good measurement here with a gauge also.
Mike

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Mike, I understand all that. Just trying to show them the flaw in their equation for wall thickness. Could also get accurate measurements with an ultrasound gauge to determine wall thicknesses at any given point accessible.

m-4

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Unfortunately, the barrel outside diameter is too small for virtually all commercially availiable ultrasonic transducers to get an accurate reading. That is why they are not used in this application.

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