A little motivation required. - UTG Pro Super Slim Picatinny RMR Low Profile Mount

I bought this to mount my RMR onto my Remington 870. The RMR fit onto the mount just fine but then when I tried to mount it to the XS Sights rail it wouldn’t fit on. The three lugs on the mount didn’t fit into the slots on the rail. I removed the sight from the mount and used a dead blow hammer to tap it into the slots. Afterwards I remounted the sight and it seems fine. Not sure which was really out of spec but I imagine it was the mount. But for less than $30 I guess I can’t complain. Seems solid though and I will find out next week. If it holds up to slugs then I’m happy.