When I first started attending matches at the Gem Ranch in the 1980's, my bench gun was a Ballard Pacific in..40-90.  It's what I had, so it's what I shot.  Load was a Pool 382 gr b/s, 24 gr SR4759, 1/2 gr of Kapoc on the powder and WWLP.  Even with my limited abilities, the rifle usually placed in the benchrest matches, and was, and still is, capable of 3/8" groups.  Later, when I wanted a rifle for both offhand and bench, I went with the 32-40, now am shooting a 28-30, and hope to finish and move to a 25-21 soon.  That 40-50 with a 330 to 370 gr bullet will do fine.  Stay away from those 430 gr rambusters, they're overkill at 200 yds.  Shoot what you've got, and what you want.  The first 250 shot at our club was with a 40-65 in a Browning BPCR.

Jerry