Bill, eight bore,
Thanks for the information. There are no underbarrel lumps with chamfered surfaces to push back Purdey underbolts and otherwise act on the crossbolt, so I can see how the 'trip' is necessary.
The gun was loaned to me recently. As far as I can see it is a 1926 12-bore NID, grade 4 (engraved duck on left side plate, pheasant on right and snipe under the action) with grade 7 checkering.
By English standards that is a heavy gun, at 9lbs exactly. More the weight we would expect from a 10-bore. It's an impressive beast!
Nigel
