Simple and it works - NcStar Universal 12 Gauge Shotshell Side Saddle 4/6 Capacity A12SH4/6

This is a nice item, it is really easy to setup, just trim the hook and loop to fit and put it on your gun. If you had multiple shotguns you could get extra hook and loop and move the shell holder from gun to gun. Surprisingly durable I haven't had it fall off at all. It of course does have some play if you really handle it rough, a little wiggling because its not bolted on. I like it because my shotgun pulls double duty as a predator rig and home defense gun so I can take it on or off as I please.
Pros: Ease of setup, removable
Cons: Not as durable as a bolt mount

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