Not just the factory extended tubes - everyone was out, even the expensive Wilson Combat models! I eventually just gave up and bought an over-long Choate tube; cut it down with a pipe-cutter and voilaI've been trying to clone my 870 express into an 870 Police style gun with the rifle sights... Do you know how hard it was a few months ago to find a factory remington extended mag tube? It was OOS everywhere, and where it was in stock, it was marked up to $130 on brownells when its MSRP is around $45-$50.
for less money you can buy a Mossber 930 at walmart........I have a Mossberg 500 (7+1 capacity) that bought 15 years ago and been using for 3 gun match and still strong.