I used a 18.5" barrel on my 870 20 gauge with handloaded tss #9's the 1st year I loaded my own and it delivered excellent patterns and I killed my limit in Tn. Shots were from 20 to just a touch over 45 and all were clean kills, best I remember my 10" counts were in the 320 /180 range, I was using a Indian Creek. 555 BDS choke.