US Military uses the Mossberg 500 action. The 870 was as solid as they come until the last decade IMHO, but for my money, on a lower dollar shotgun, the 500 is an excellent choice. A Mossberg 835 is nearly indestructable and shoots everything they make in 12ga except slugs (You can get a slug barrel if need be).
IMHO, you're less likely to get a lemon in a Mossberg shotgun than you are in a Remington 870 or 887...