Interesting. Of course the 700 eventually evolved into a series of guns of different grades, as did the 400. The 700 was essentially the equivalent of the Grade III 400; the 702, which added drop points, better wood and more engraving like the Grade II 400; and the 701 as the top of the line of the 700 series, like the Grade I 400. I recently acquired a 720, which is a 702 made for the US market with 3" chambers. All the 720 guns--or at least those imported by Harrington and Richardson--were choked 1/4 and 3/4. Were I to shoot
nontoxic shot in mine, I would do as you have done: I'd be fine with steel in the R barrel, but I'd go with something like Bismuth or Tungsten Matrix in the more tightly choked L barrel.