So is there a way to hook this on to your shotgun securely without drilling and tapping? I got the one that has the 6 shot carrier and rail all in one. I have heard people having problems with cycling after installing it the normal way.
Do you mean this one?
Negative this is the one I am speaking of.
Ah, I have the other one, which utilizes the receiver pins. I’m sorry I could not be of more use. 
Could you open up the outside of two the shell holders? That might allow you to drill and countersink a pair of holes. That possibly could allow you to utilize the receiver pins.
Lot of dang work, however…