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Forums10
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Jul 28th, 2025
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Joined: Jul 2010
Posts: 707
Sidelock
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OP
Sidelock
Joined: Jul 2010
Posts: 707 |
I know how I do my measurements and I know how the german and english proof houses create their "minimum recommendations before reproof", but I thought a thread with comments by experts is in order.
Anyone more qualified than me care to make recommendations on where you like to take bore measurements and how you reconcile a gun with good walls (but a thin area) versus a gun that is overall pretty good (e.g. .027") but pretty slight all around?
I personally hate taking bore measurements because I've got a vise mountable gauge for horizontal use and it takes a lot of tweaking and messing around to make sure i've got it right.
Any constructive thoughts?
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Joined: May 2003
Posts: 270 Likes: 31
Sidelock
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Sidelock
Joined: May 2003
Posts: 270 Likes: 31 |
Surprised you haven't been inundated with answers yet. I was taught to use the following on English 12 bore Game guns.
Pre 1925 Proofs
Chamber Immediately prior to Forcing Cone. .105"
9" from Breech .045"
4-8" back from muzzle .025"
Post 1925 proofs:-
.100"
.040"
.025-.020"min
Smaller Gauges May require a little more.
Hope this helps get the discussion started.
Hugh Lomas,
H.G.Lomas Gunmakers Inc.
920 876 3745
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Joined: Nov 2005
Posts: 4,598
Sidelock
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Sidelock
Joined: Nov 2005
Posts: 4,598 |
I have posted this many times. It is a good starting guide. It is from 1891.  Pete
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Joined: May 2010
Posts: 1,543 Likes: 102
Sidelock
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Sidelock
Joined: May 2010
Posts: 1,543 Likes: 102 |
Wall thickness can depend on the gunmaker ,the the age, the material its made of and the use its going to get. Although there are several theories as to what is an ideal,or what constututes a safe margin will also depend on these points.
It was accepted in the Birminghan that a Greener for example needed to have heavier walls than the equivolent Webley.This was down to the simple fact that Webley used a "higher" spec steel.
There is no hard and fast rule as to the maximum or minimum wall thickness "recommended " wall thickness was invented by the auction houses as a way of selling worn out guns with no come back ,I belive this has now stopped and they just publish a list of bore sizes so it down to the buyers discresion. Although most will not sell agun at under .015"other than as a stock and action.
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Joined: Jul 2010
Posts: 707
Sidelock
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OP
Sidelock
Joined: Jul 2010
Posts: 707 |
Great input.
One thing I've noticed is that advertisers (dealers) do not speak apples to apples.
One dealer will give "Minimum Wall Thickness" to mean the minimum wall thickness ANYWHERE in the bore of the gun.
Another dealer will say "Minimum Wall Thickness" and mean the minimum wall at 9" from the muzzle.
lastly, I've noticed people stating wall thickness at 9", but I believe from the numbers they are espousing, they are measuring 9" from the breech, not the bore.
What is the ethical, technically appropriate way to describe a gun and which ways are considered unscrupulous?
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Joined: Apr 2005
Posts: 1,698 Likes: 46
Sidelock
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Sidelock
Joined: Apr 2005
Posts: 1,698 Likes: 46 |
I think it is necessary to thoroughly examine barrels completely with a wall thickness gauge and if at all possible an endoscope. Ballistix's Clarke is a fine example of how things can go wrong. That incident could have had very serious repercussions.
We also went through a phase when the gunmakers were obsessed with producing light guns, and it was common practice to produce lightweight barrels, those barrels could still be out there one hundred years later plus a hone or two to remove pitting. Caveat Emptor. Buyer Beware.
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Joined: Jul 2005
Posts: 7,065 Likes: 1
Sidelock
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Sidelock
Joined: Jul 2005
Posts: 7,065 Likes: 1 |
I have many light bird guns with unaltered 2-5/8" chamber that have less that .100" at the end of the chamber. These guns have the correct end chamber diameter. If, after I have had a cup of coffee, I can remember the post I will copy the list and paste them here again. They were made in the US, Britain, and Europe.
Best,
Mike
Last edited by AmarilloMike; 08/25/11 07:13 AM.
I am glad to be here.
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Joined: Jul 2005
Posts: 7,065 Likes: 1
Sidelock
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Sidelock
Joined: Jul 2005
Posts: 7,065 Likes: 1 |
I quoted myself below from this thread (so we know the source is reliable)  : http://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=224972&page=1I sure have a lot of doubles with original chambers and forcing cones with wall thicknesses way below .100" at the end of the chamber.
Fox A grade 16ga, 26" barrels, 2-7/16" chamber, 0.085" and 0.086" minimum wall thickness at the end of the chambers, .734" and .734" diameter at the end of the chambers, 5/8" long forcing cones, #4 barrels, gun weighs 5lbs 9oz, serial 302XXX.
Parker VH O Frame 16ga, 28" steel barrels, serial 134XXX, 2-9/16" chamber, .082" and 0.085" minimum wall thickness at the end of the chambers, 0.730" and 0.732" end chamber diameters, 3lbs 2oz unstruck barrel weight, gun weighs 5lbs 14oz.
Fox XE 16ga, 30" barrels, serial 301xxx, .072" and .080" minimum wall at chamber ends, 2-7/16" chambers, .733" and .733" end chamber diameters, gun weighs 6lbs 3oz
Parker DHE 16ga, 32" steel barrels, serial 212XXX, 0.090" and 0.092" minimum wall thickness at chamber ends, 2-9/16" chambers, .735" and .736" diameter at chamber ends, barrel unstruck barrel weight 3lbs 11oz, gun weighs 7lbs 4oz.
Lefever H grade 16 gauge, 28" twist barrels, .090" and .092" minimum wall thickness at chamber ends, 2-5/8" chambers, .729" and .728" diameter at chamber ends. Gun weighs 6lbs 4oz
Ithaca Flues Grade 4E 16 gauge, 28" Krupp fluid steel barrels, 0.091" and 0.092" minimum wall thickness at the end of 2-5/8" chambers, daimeters of .728" and .730" at the end of the chambers, gun weighs 6lbs 6ounces.
Parker DH 12 bore, 28" Damascus barrels, 1 frame, .086" and .090" minimum wall thickness at end of the 2-5/8" chambers, gun weighs 6lbs 14oz. Serial #84XXX, My Skeets gauges are in capable of measuring the diameters at the end of the chamber.
Bissel Birmingham boxlock, 20 gauge, 25" steel barrels, made in the 1920s, .084" and .092" minimum wall thickness at the chamber ends, 2-1/2" chambers. My Skeets gauges are in capable of measuring the diameters at the end of the chamber. Weighs 5lbs 7oz. And Here is another data point: AYA #1 20 bore sidelock, factory 2-3/4" (70mm) chambers, 30" barrels, built and proofed in 2006, .092" and .091" minimum wall thickness at the end of the chambers. Skeets gauges unable to measure chamber diameter. Gun weighs 5lbs 13oz. And Couple more data points:
My shooting student Joe Wood checked his minty Webley 700 6lb 4oz 12 bore, .092" and .090" minimum wall thickness at the end of the chambers. Factory 2-3/4" original chambers.
One of his DH 12 bore 1 frame Damascus 28" barreled guns weighs 6lbs 8oz and has .092 and .095" at the barrels. Original 2-1/2" chambers.
Last edited by AmarilloMike; 08/25/11 07:39 AM.
I am glad to be here.
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