> It also appears that a previous owner added the bumper to the
> bottom of the magazine,

I was wondering about that, as all three are like that but two of them are hardly used. Or perhaps not at all.
Actually, the gun itself doesn't seem used a lot, the previous owner didn't shoot it much during the 11(?) years he owned it (so the first can't have had it very long) and I even got some boxes of partially used factory ammunition with it, as well as handloading tools. Naturally he's more competitive here in Sweden with his SIG P210 in 7.65.

> and possibly the extended slide stop.

Yes, it's from Wilson Combat.

> How many recoil springs are in your "new" Scoremaster?

Two. The original short one has been replaced with a softer one from Wilson Combat, the original long one with one from Detonics accompanied by a service notice. All original parts (even the spring Detonics said to throw away) have been saved and marked as such.