Probably simular to Britain nowadays, up til about 1920 our gun control was non existant and seen as not needed but gradually increased after that, with most guns banned after Hungerford and Dunblaine (though the events of the last couple of months prove our controls aren't that effective).
Sad to say of course while it might get guns out of ordinary peoples hands, you'll still have criminals with guns, they manage to sneak them into Britain (or just make them here) and America is alot easier to smuggle into with those massive borders.