Salopian,To this "Point" I've had No problems with either of the Proof houses "Damaging Guns Sent to them for Proofing. My 1st gun sent by The Late Alf Gritt of Chaplins Gunmakers, Winchester,Eng.(1966) had New Brummie Bbls.Best Quality Workmanship, made and fitted so that the "Minty Orig Damascus" could still be used.The Newtubes" @ 2.3/4"X 1.1/4oz were 90%x90% at 35yds.Great Boxed Pigeon & Doves in Mexico Chokes. I chose not to put the Damascus through "Nitro" as Alf Gritt said to stay with 2.1/2"-1.1/8th oz...I've used them mostly with "Black" at"Old Gun Shoots"Have Photo of"El President'e"(Eddy Reincarnate the VII) Ray Poudre shooting '5 Stand at Geoff Gaebe's Grounds!... Years ago, I loaned a "Sport" the W.W.Greener which I had "Cased with both pairs of Bbls.I was not aware that "Said sport",When shooting at ducks in Minn.was putting 1.3/8ozNitro #4 shot through the orig. damas. Bbls.I wonder how close to a London Proof Load he tested my Old Greener for????Had my Old Friend Alf Gallifent check them very carefully after he raised a small dent that appeared when "Photog T.Allan was shooting 2000 pics for one of his projects here at the museum of P/Mess. I have a Clients Dickson R/Action with "New Barrels By The Sleeving Method" going to London for Proofing....errrr maybe!!!cc/dt