Miller, I think the BSA might have been the first gun with the same type dovetail chopper lump as the 21 has--although I would not swear to that.
Ted, I'd say that either the stock or the sleeving might have done unusual things to the balance. One wouldn't know that without the gun in one's hands. But you're absolutely right in indicating that the only way one of relatively modest means will ever own a Purdey or Boss would be on a gun such as this. The only Purdey I've owned--and expect will ever own--was sleeved, and had choke tubes no less! But as you've pointed out with this Boss, that probably made it a better "shooter" than if it still had its 1880's vintage original barrels.
If you get it, I'll be interested to hear how it works out for you.
