The winchester 1300 I own really likes the Ko slugs. I have both a rifled barrel and 18" smooth barrel with rifle sights. With the rifled barrel and scope it will put 3 Win. sabots into 2" at 100 yds.
With the smooth barrel it does not like anything from federal and only winchester in the 3" mag. slugs.
What it really shoots well out of the smooth barrel is the Brenneke Ko slugs.
Three will stay on an 8" plate at 100 yds.
As far as penetration and knockdown power, I have shot two deer with rifled slugs . First deer was hit thru the lungs from about 30 yds. and managed to run, hobble, limp, maybe 50 yds. No slug recovery. The second deer was hit in the center of the chest head on, from about 60 yds. and ran maybe 30 ft.
The Win. 425 or so gr. slug was recovered in the ham of this deer.
It was flattened to about 1/4" thick, was nearly the dia. of a soda can top and looked exactly like a miniature horseshoe. Penetration would be 3 ft. plus.