Is there a common standard of thickness for the cylinder portion of a 12 gauge and 20 gauge. I am talking abouth just before you come to the choked part
THanks All

Varies by manufacturer, chamber size (pressure) removable choke,lenght and purpose, I have a set of trap barrels for my Citori which are chambered 2.75 and designated as 325l meaning light, compared to the Invector plus 3" barrels if feels and looks like a 20 gauge

Hmmm interesting. so there is nothing much of a standard for gauges...Do you know how far back from the end the chokes start?

You may try asking on the gunsmithing forum. What you are asking for is the minimum barrel wall thickness(MBWT). I know I was once looking at an old Fox that had a MBWT of .025"; which is thin.

It also depends on company, era, country, etc...Most older American doubles are overbuilt and have thick barrels, where as some of the higher end European guns of the time where thinner and proofed to certain loads.


EDIT: I now see you might be talking about bore diameter. The standard for 12ga is about .729". Kolar makes one that is .750". Invector + barrels run .742". This is another reason why I wished choke tube companys would use nunber designations to describe constriction rather than C, IC, MOD, FULL, etc...

Most British guns maybe run around 30 thou. Anything below 25 tho is considered "buy with caution".

Not because it is unsafe but that if subsequently dented raising the dent may be impossible as not enough metal exists to then strike off the raised dent.

Thanks all, seems a lot of variability to be delat with...Thank you

There is also a bit of an age difference in that many guns before steel shot can have thinner barrels than the same brand and model after, just due to the extra stress of shooting steel.

From what I understand, the Brit Proof House will Ok a gun with barrels as thin as .017 inches. The thickness of their barrels was dependent on at least two factors. The ton proof level and the weight needed to balance the gun near the hinge pin. Wall thickness of .035 was considered quite thick. A 2 3/4 " 3 1/2 ton gun would have thicker barrels than a 2 1/2" 3 ton proof gun. Also barrel bore diameters could vary from .729 to .744.

465H&H

quote:

Originally posted by 465H&H:
From what I understand, the Brit Proof House will Ok a gun with barrels as thin as .017 inches. The thickness of their barrels was dependent on at least two factors. The ton proof level and the weight needed to balance the gun near the hinge pin. Wall thickness of .035 was considered quite thick. A 2 3/4 " 3 1/2 ton gun would have thicker barrels than a 2 1/2" 3 ton proof gun. Also barrel bore diameters could vary from .729 to .744.

465H&H

British proof is not dependent on barrel wall measurements, or at least not directly - there is no "minimum" thickness requirement.

When a gun is originally proofed when new, the bore diameter is measured and stamped on the gun, typically this will be .729" for a British gun. If the bore diameter is later measured and found to be more than .008" bigger at any spot than the original 729 thou,(ie bore diameter at more than .737") it is deemed "out of proof" and cannot legally be sold.

You can resubmit any gun with any barrel wall measurement for reproof - at your own risk, if it blows up with the proof charge it is your loss.

Guns down around 20 thou pass proof all the time and may have a long life ahead of them.

The classic case is of a Purdey which passed proof with barrel walls down to .007".