[TheKlawMan]

Curious about your problem. The last time I looked at an 870 tactical, it had a 6 round magazine capacity, but that was actually a 4 round magazine with a 2 shell factory extension. Recently I believe I heard that some tactical type 870's came with an actual 6 round magazine tube. It isn't clear to me but sounds as if your rifled 23" would fit the old style Tactical model, if the 2 shot extension was removed. If theis makes any sense, and if you already bought the 23" barrel, you could cosnsider having a gun smith outfit your gunn with an old style 4" capacity magazinr tube (and if you want a 2 shot extension". That magazine is braised to the receiver, unlike a Mossberg, so it is likely a job for a gun smith.

Befrore doing all that I would call Remington and ask them if they are coming out with that barrel for a 6 shell magazine.

Perhaps I have things backwards. Pictures of the problem would help. If the lug ring does slide down over the magzine tube, what Virginian in LA says about a spacer would work. That sounds like what some guys did to make Remington barrels fit on some Chinese knock offs. (It's tube was also longer than the Remington. )

Here is a thread talking about using a spacer to fit a Remington barrel similar to Virginian-in-LA's suggestion. I cringe at the thought of PVC and this guy used EMT tubing shimmed with some flashing.