I would choose an English wildfowling boxlock in 3 inch chambering , 1 1/2 oz proofed barrels 30 to 32 inch in length and weighing between 7 1/2 lb to 8 1/2 lb . The BSA has a reputation for strength but any of the old wildfowling guns would do. Thomas Bland’s “Brent”for example or Greener’s “Empire”. Guns by Tolley , Lewis ,Thomas Wild,Gallyons, or any provincial maker from around the wildfowling estuaries there is no lack of choice.Killing two birds with one stone a Dickson round action in 3 inch chambering. Some of these old wildfowling pieces though subject to harsh conditions have probably fired relatively few shots so should have plenty of serviceable life and should easily handle 7/8 oz loads all day long. The absence of ejectors ,common with these guns ,is one less thing to go wrong.
Graham MacKinlay has a “Brent” on offer for under £500 and £500 to £1250 is as much as you would need to spend if you were to shop around though obviously you would have to pay a good bit more for the Dickson.
A more modern option is the AYA 722 , a single triggered sidelock with pistol grip designed for sporting clays and around 7lb in weight.

Last edited by Konor3inch; 01/19/21 07:00 PM. Reason: Add last sentence