I have a double rifle in 318 Westley Richards made by Thomas Bland for W.D.M.Bell. I would like to find out why the barrels are 338 across the grooves, rather than .330, as the books say the bullets are supposed to be sized at.
I have fired .338 diameter bullets from it, with cases thinned at the neck to allow the larger bullets to fit properly, and the brass to release the bullets on firing. I have had good results with 180 grain bullets, and 200 grain bullets, although the gun seems to be regulated for 180's.
Any help in this matter will be of great assistance.