I would agree that in a perfect world, a MWT of 0.023-0.025 is the ideal but then I have seen a 1970's H&H Royal, not a light weight model, with original MWT of 0.019'. This is probably not very scientific but has served us well till now. Perhaps I mix with the wrong people (!) but everybody seems to concern themselves with MWT throughout the barrel length, I certainly only quote this measurement on my stock descriptions. It is perhaps interesting that I have never come across any one in the English trade who took much notice of the WT at 9' other than barrel makers themselves. I guess the topic has moved on but in referance to the original topic posting: 6mm (.024').Ĭertainly bbls have passed proof with thinner walls in the forward portion, but personally I would not feel comfortable with any less in the chamber area & more would be better. It was further stated the minimum thickness in the forward third of the bbls should be. No mention of reduction for the smaller bores. This was stated to be with 'Ordinary Good Steel' while if 'Sppecial Steel' was used these could be reduced by no more than. Unless a very long cone the cone will normally taper more than the OD of the bbl so 'Ahead of the cone (as in front of it/forward) will be thicker than behind it (breech side) as well as the pressure will be lower there than at chamber end.Ī book I purchased many years ago (copyright 1966) entitled 'The New Hunter's Encyclopedia' had some figures they quoted as being from the German proof houses which stated min wall at forward end of chamber should be in 12, 16 & 20 ga's 2.3mm ((.0905') & for the 24 & 28 ga's with their higher pressures 2.4mm (.0945'). The point where the chamber meets the cone is generally the most critical point in a shotgun bbl. Just to be certain we are all on the same page in saying 'Ahead Of' the forcing cone are we speaking of the juncture of the chamber with the cone or the junction of the bore with the cone.

Shotgun barrel wall thickness gauge