If it's too tight you can always sand down a bit but I get your concern. There shouldn't be a need to sand down for the price.
I just installed the MIAD grip and I screwed up the threads on my lower so I'll need to retap it but that grip was pretty tight to get on, which I liked because then I know once I put the screw that thing isn't going anywhere. I just had to slide it in the right way. (that's what she said)