I've been building a youth 870 for next season. Added a shurshot stock. Had it drilled and tapped by sumtoy and used his mount for a vortex venom 3 moa. Gonna be shooting 1 5/8 oz tss #9 handloads. I've got 3 Indian creek chokes to try 555, 562, and 570. Hopefully one of those will get me 300 in the 10inch and 230 in the 20inch. I'd be happy close to those #s. Heres some pics.
https://photos.app.goo.gl/9HD0b2zP9NDFVBK72