For aftermarket, see Wisner's
; they makes excellent 5-rounders; they are marked with just a "W" on the bottom. They are available directly or from Brownell's.
If you are looking for a genuine Winchester, try Out Back Gun Parts
"Out Back Gun Parts, Inc.
2110 McLean Avenue
New Albany, IN 47150
Tuesday through Friday 10:00 AM to 5:00 PM Eastern Time"