Ted, I've never seen an automatic shotgun, but your dad probably did shoot an automatic rifle in service: BAR.
Speaking of field grade doubles, all the American classics were pretty good. Judging by the prices of used guns, the Trojan and the Sterlingworth seem to be the most sought-after. Of the classic sxs, I think the NID Field Grade is probably the most underpriced.
For an interesting all-American field grade OU, the Marlin 90 deserves consideration. I just picked one up in 12ga, excellent original condition, for a little over $300. When I gave the barrels the "ring" test, I was surprised at how "ringy" they are.
