Colt did make some like that, but they were a special request deal. One of the neighboring LE agencies ordered about 100 of them like that in the late 90’s- 16” barrels, A1 upper, and the A2 buttstock. They eventually swapped out the entire uppers for the more common detachable flat tops with an optic. Their reasoning for the A1 upper was so people would not fiddle with the rear sight adjustment (though they were individually issued, not pooled guns). They also kept them empty while in the patrol car, with a yellow mag block inserted. (But their 870 shotguns were loaded!). They also carried only 20 rd mags initially as well, but only in a stock mounted pouch.
Meanwhile the rest of us were running 6520’s, 6721’s, and then 6920’s, with 30 rd mags seated. Sometimes it pays not to work at a screwed up agency! (Not to mention, that agency really restricted rifle use, only a small percentage of their people had a rifle. We issued one to everybody.)
Anyhow since those uppers were swapped out, and they officially do not trade in their firearms (unofficially they do, I have some of their 870’s), I doubt any will ever be surplused out.
Don’t know what model number Colt gave to those rifles either. But there were indeed some made in that configuration.