Purchased this to run mini 12 gauge shells in my Mossberg 500. The Mini-Clip was easy to install and fit nicely. Much to my dismay, it would not allow the shells to feed. It did not leave enough room to cycle the shells, and they would catch on the back end of the barrel that protruded into the chamber. I sent a question to the manufacturer by email and was answered quite promptly, by Bill Nolan the developer of the Mini-Clip even though it was a holiday and he was traveling. He clarified some things in his answer and when I checked the SAAMI specs it turns out my shells are 1/16 inch longer than they should be and thus will not work with the Mini-Clip. So even though I can't use the unit yet this gets a 5-star review due to customer support and the quality, fit and finish of the Mini-Clip. I look forward to using it.