Notes on Proof and Barrel Wall Thickness of Shotguns
Here at George Gibbs Ltd we have a policy of selling 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 (for shotguns of 28 bore to 12 bore inc)
We will sell guns with measurements of less than these figures but will indicate the sizes and offer the gun at a reduced price. The reason for this is we hope that any gun we sell will give years of service for the new owner and with our minimum measurements,we feel we can repair even quite severe damage to barrels eg dents , pitting , without compromising the owners investment in the gun.
Our experience tells us that shotgun barrels with a minimum wall thickness below .025" ( 25 thousands of an inch) are not dangerous to shoot nor are they more likley to fail a proof or reproof test , however the thinner the barrel the easier it is to dent them and the harder it is to repair them , indeed the repair of thin barrels makes the barrels even thinner thereby compounding the problem ! This is why we adopt our policy on wall thickness , in order as practical gunmakers to give you , our customers , good service and peace of mind .
This is what I find out here
www.gibbsgunmakers.com