I just spent two days in a shotgun class with Hershel Davis at Halo group in CA. There were only 7 in the class, but we put 350 rounds down range, and I got to see several combat shotgun types in action.
My observations:
Benelli auto-loader - FAST, FAST, FAST. 5 shots on metal poppers at 10 yards in just under 2 seconds. However, it was very picky about ammo, would not cycle some low base shells reliably, would not cycle federal premium slugs, and shot high and right all weekend, even with the site adjusted all the way down.
Vang Comp Remington 870' (3) - Nothing patterned better out to 35 yards than these shotguns. One of them was still holding 4" at 35 yards with 00 buck. 1 had feed problems with the extended tube, consistently sticking. The follower would stick compressed and would not feed shells. This is pretty easily rectified with a little smoothing of the tube, but for the price, should not have been happening. I do not know why, but neither Vang Comp'd 870 on the line ran real fast in the speed drills. The third one was operated by a guy that was a bit older and not real fast anyway.
Mossberg 500 - Plain jane (mine and one other). My pump was the fastest on the line, however it patterns pretty wide, forcing a swap to buck at 10 yards, and slugs at 25. No rifle sites on mine either, making long slug shots harder. Nothing on the line was more reliable. No problems all weekend with either Mossberg.
I would look for the following, no matter what the brand:
Ghost Ring sites
18 - 20" cylinder bore
Pump action
Extended magazine tube (more than 5 on an autoloader makes it a AW, BTW)
Good sling loops and a sling
Side saddle shell holder
Plastic stocks and forearm. No wood.
Nice to have but not absolutely necessary:
Compensated barrel
Worked barrel to improve pattern and accuracy (Vang Comp or Scattergun seem to be popular and effective)
Flashlight forearm
If you buy a Remington 870, make sure to get the short forearm version so it does not interfere with adding a side saddle and cause some other problems when used as a defensive shotgun.
Check out
www.vangcomp.com for a good price on a modified Mossberg 590A1 that is on sale right now.
The 590A1 would be my choice at the sale price listed. Heavy barrel, Ghost Ring sites, compensated and tweaked for pattern, all metal trigger group parts, extended magazine.
Ray