I would like to thank L. Brown for confirming that at least two of those 2 1/2 inch chambered British doubles do indeed have 2 1/2 inch chambers. Hopefully, this is true in general.

Well before magnumitus became endemic, 65, 67 and 70 mm hulls were sometimes loaded with an additional 1/8 to 3/8 oz of shot and reduced powder charges. Old loading manuals often include various such loads, generally with pressure data showing normal chamber pressures. I have shot lots of those in older, but still strong, doubles, with heavy loads of larger shot (the ancient low velocity, heavy shot approach for waterfowl, etc.). Don't recall there ever being a fuss about these loads being unsafe in guns designed to hande these chamber and barrel pressures and breechface forces, guns still in excellent condition.

I do agree with Smallbore's concern about an unsavvy shooter using highpressure USA shotshells in an actual 2 1/2 inch chambered, lightweight British double. Do many such folks follow this Board? However, this is a BB where the savvy reloader and shooter can get rather detailed informations about ways to increase the versatility and satisfaction of their hobby. Many of us follow this BB closely for just such informations. So, can there be an acceptable balance of these two concerns?

Niklas