Barrel wall thickness
 

What is the minimum barrel wall thickness that you would shoot in a 12 Ga. Parker.I would like your feedback and that is shooting RST shells. Considering there is no pitting or damage to the barrels other than just shooting wear.Thanks Thomas

I guess the biggest question is where the thin spot is, but the industry standard is .025 and most will say .020 isn't a problem if your using RST's. Use your judgment on the condition of the barrels in and out, and for some folks (but not me) the type of steel. For years I shot Remington Express loads out of a 16 ga. with .018" walls, I bought it from a member here who advertised guns for sale in a retail market place and trusted it was safe to shoot. I might not recommend doing that, but it's a good test of Titanic steel barrels.

I often hear 25 thousands mentioned as a standard and I understand in some conditions the Birmingham Proof house will accept 20.

the thinest damascus I have, that I shoot is just with my very own eyes and hands, is a bit over 30.

A reminder that any "minimum" barrel wall thickness you choose to adhere to must be no closer to the breech than 10" - 12" at a minimum.

That isn't quite right, in a direct e-mail correspondence I had with the chief inspector of The Birmingham Proof House he says that they will inform their customers when the MWT is thinner than .020, even though the barrels may have passed proof thinner than .020.

thanks - at least I said "I understand" not "I know" :)

I still like 30+

http://parkerguns.org/pages/faq/BarrelThickness.htm

I just noticed that the barrel thickness image is missing the source -

The Field March 7, 1891 Vol 77:325

And some more sources that could be added to the FAQ

Christopher Austyn Modern Sporting Guns
"There is no legal minimum thickness for a shotgun barrel, although the British Gun Trade Association recommends 20 thousandths of an inch as a general minimum."

Courtesy of Hugh Lomas for English 12 bore Game guns. Small gauge guns may require additional thickness.
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"minimum

Michael Lynch, the chief inspector of The Birmingham Proof House, states that they inform customers only if the MWT is below .020" after having passed proof.

George Gibbs Ltd will sell secondhand shotguns with a minimum of .004" of proof size remaining and a minimum of .025" of barrel wall thickness at 9" from the muzzle.
http://gibbsgunmakers.com/Notes%20on...20Shotguns.htm

Courtesy of Austin Hogan
Analysis of 22 twelve gauge Parker barrel sets show the average minimum barrel thickness at 24 inches is .031 inches. Minimum thickness at 18 inches was about .050 inches.
Eccentricity may cause portions of the barrel to be thinner.

Drew,
What does the minimum of .004" proof size remaining mean?

Based on these standards Chris

http://pic20.picturetrail.com:80/VOL.../383123870.jpg

So if the 12b barrels are marked 729, Gibbs will sell the gun with a bore of no more than .733. If 13/1, no more than .723.

my gunsmith, who has over 60 years of experience, recommends .030 of an inch as the minimum for safe shooting.