Great for always having rounds on hand - GunMate Buttstock Shell Holder Black Rifle

These work great, i have one on a 308 rifle, I had to cut a small hole in the bottom of one of these so that the swivel bolt for the sling would fit through, i cut it into the non-seam side and its holding up fine. Also the rifle version of this will hold 4-10 shells fine.
Pros: Cheap price, Rifle version works with 4-10 shotgun shells too
Cons: None

This review was written in the old system and had content requirements that are different than reviews written today.