Silvers, British game guns get as much shooting as their NA counterparts. In the grand old days, many of the top shots would easily fire off 5000 rounds in a week of pheasant or grouse shooting. There is no problem as long as the proper loads are used. You would soon rattle a best gun loose if you used NA magnum loads in it.
As for repairs of guns whose makers no longer exist, this is not a problem since any replacement is a one off anyway, and a new tumbler on a gun will probably cost the same whether it is a Purdey or one of the long disappeared provincial makers.
Buy a gun you like, shoot as many appropriate shells as you want and accept that spares will have to be made on a one off basis for any British gun.
