magtube extension for H&R partner pump

[MoBart]

I want to add an extension to my partner pump, Im assuming tube fitting an 870 should fit, excet the diffrence in barrel length between the end of the tube and barrel ring (if thats the right nomenclature) and the end of the barrell. Anyone have any suggestions? I have seen ome by wilson combat but $80 to add another round to a $200 shotgun seems kinda dumb to me.

 

[thinktwice]

If you take out the plug at the very top end of the magazine you can easily add another round. It doesn't hurt the gun or have any bearing on the gun. The mag spring just rest inside the mag cap.