I'm sorry for your troubles man but that is known as gunsmithing...
Parts are usually small so they can be fit the way the user wants. Granted in your case it seems a bit worse than usual but some heat or sand paper on the inside of the grip will make that a great shooter.
Parts that are tight are never a problem in my eyes. If the magpul grip was too big and had a lot of slop, the would be crappy QC IMHO