he, he, he, one of these days I'm gonna find "another" 870 3" chamber ~ 23" in length vent rib with oversize front and mid bead set - and have external knurled screw in chokes installed...he, he, he... Yep - I DO know something....*grin*
Proven by me in both 12 and 20 for 870, 37s and 1300 ...the 1300 is avail from factory as Upland Special and Ithaca has one as well.....*grin* ....