Toby, if RA is talking about a fixed choke sleeve, would it not be less of a problem with thin muzzles? I would think that the only issue would be the danger of damaging the muzzles in between the time they were reamed and the time the sleeve was permanently installed. With interchangeable tubes the danger of damage is there every time a tube is removed and replaced.
FWIW, I had Briley thread a very old Perazzi MX8, imported by Ithaca, for tubes about 10 years ago. It left the muzzle walls very thin, but they did an excellent job, I thought. My buddy at CompNChoke did lots of these jobs during that time, and he didn't want to do mine due to the thinness at the muzzles. He suggested I consult Briley and go with their recommendation, thumbs up or thumbs down, which I did. That said, I would not do it to that particular gun again. Why? I sold it to a good friend who wanted it. He shot it about a year and shot the end off one of the barrels, ruining the set. I thought he let a tube back out during shooting the round of clays, allowing plastic shotcup material to begin shaving off and packing under the rear of the tube, until it became an obstruction and "blew". But, he says that did not happen, so if it didn't the only other reasonable explanation is that the barrel wall was so thin at the threads that it eventually fatigued and failed. I have enough suspicion that he is right that I just wouldn't take that chance again with thin walled muzzles.
SRH
