I haven’t tried a 21" barrel yet but my SBEII has a 24" barrel and I shoot it a lot better than the longer barrels. I hear the same thing you do from people about the length and the loudness of it, especially when I’m in a duck blind with others. I think the reason this shoots well for me is because of my size. I’m only 5’5" and the shorter barrel just swings right for me. Longer barrels seem to lag behind when I’m swinging through a target. Over all this shotgun fits me really well. I’m sure that has a lot to do with it also.
I don’t know what the reason is but it is evident on the skeet range and in the field. I’m 6’1" and love my carbines, I did have an 18" M2 Tactical but the 21" M1 is all I have now. If I had a regular stock on the M2 Tactical, it would probably still be in the safe for coyote and turkey hunting.
I actually traded the M2 Tactical for a Rem 700 XCR Tactical in 308 with of course a 20" barrel…
I think Gutshot John pretty much said it. The 870 Express isn’t perfect, but if you make the necessary upgrades (as I had my friend do when he recently bought his Express) you should be good to go. Is the Wingmaster of higher quality? Sure. But you still get plenty quality with the Express model provided that you purchase the (nearly) obilgatory upgrade parts.
can’t beat the old 270$ 870 pump
I’ll toss in a recommendation or two. If you are a walking upland hunter, grouse, woodcock, rabbits, etc. a light 20 is the way to go (at least for me). I had an 870 Special Field with an english stock I used for a few years. The 21" barrel was no hindrance and the gun was easy to carry all day. If you need a longer barrel this may not be for you, but for a hunting gun it was easy to maneuver in and out thickets, etc. I beleive you’ll have to look for a used one and the barrels are fixed choke.
Second recommendation is actually a 28 gauge. The Franchi AL 48 is also a walking hunters friend. Very lightweight semiauto, not sure what the 20 gauge would weigh but it’s less than 6 lbs. I bought one after hunting a couple of days with a friends Sportmans 48.
Current upland gun is a Stevens 5100 20 gauge that was my wife’s great grandfather’s. Nice double 20 with real walnut and checkering. Nothing fancy, a working man’s gun from the 40’s that works.
One cant go wrong with a 12ga pump gun with choke tubes. Win1300, or Rem870. Can be used for ANY type of hunting situation.