Opie-In was nice enough to share this info...
I did some patterning with my 870 Cyl bore 18" today...
Federal Tactical 2 3/4 00 Buck #LE132 00
7yards 6.5in spread
10yrds 8.5in spread
15yrds 12in spread
20yrds 8/9 pellets on IDPA target...
Remington Reduced Recoil 2 3/4 00 buck #RR12-00BK
7 yards 7.5in
20 yards 7/9 pellets on IDPA target...
The longest shot in my house is approx 10 yards so either works fine for me. All shotguns pattern differently.......If you require shots past 15yrds you will want to start looking at Imp Cyl or tighter chokes in my opinion.