Let me get this right - you went from an auto to a pump, and a plastic military-style one at that, and picked up 4 birds per round in a game involving shooting doubles? I guess you weren't that active of a skeet shooter before or scoring very highly?
Yup and yup. I was *really* new to skeet at the time. The 1100 didn't fit me well at all and the hard plastic buttplate made it very uncomfortable to shoot. Flinches don't help accuracy.
With the 870 Tactical, initial fit was better and I wasn't fearing the recoil (note: the SpecOps stock eats up the recoil quite a bit). I really didn't have a problem with the pump action; I lost a fraction of a second on the doubles, but I was still able to pick them up. As I practiced more, as I said, I outgrew it.
My next gun was a Remington 105CTi II. Again, better fit due to a more consistent cheek weld. It was with this gun I shot my first straight, but my scores tended to be in the low 20s most of the time. While I shoot the gun reasonably well, I ran into a couple things that made me consider going to an O/U (among them, the ability to shoot lighter loads and shotshell reloading).
Now I have a Browning Citori XS with the adjustable stock, and I'm still getting used to it. I'm a workin' man, so I only manage the time to shoot about 3-4 rounds/week. Since winter only just lifted a couple weeks back, I'm still getting back into the swing of things.
That 870 Tactical was not ideal, but it was good enough for where I was at the time. As I said, it is the kind of thing somebody who shoots a fair amount will outgrow quickly, but to a new skeet shooter, it's definitely a workable gun. I have shot with an old timer with a well worn 870 who did incredibly well, but yes, there's a big reason the folks seriously into the game have O/Us.
The Olympians aren't using Perazzis and the like instead of a well worn 870 Wingmaster because they all found some for dirt cheap. But then again, it takes a while before a shooter can really justify that kind of thing. Sure, starting out with one won't hurt, but it helps if you grow into such things. IMO, you appreciate some of the finer features more. I know there's several things about my Citori I appreciate because I've used less suitable guns in the past.