H & R shotgun side mounted shell holder

Question
I have a H&R Model NP1P18 12ga shotgun that I would like to mount a side reciever shell holder. Will a shell holder for an 870 Remington shotgun fit?

Answer
No, SideSaddles such as those made by TacStar attach to the gun using the retaining pins that hold the trigger housing in the gun. The pins are replaced with through-screws that hold the SideSaddle on and the trigger housing in place.

I have not looked closely at the H&R (it looks and is priced identically to a gun that was being imported from China under a different name a few years ago, and I suspect it's the same gun), but if the holes are in a significantly different place than the Remington's it would be possible for you to modify the carrier by drilling holes that lined up with the H&R's retaining pins and tapping them to accept the through-screws.