So I picked up a YHM 12.5 inch free float quad rail on eBay today for my bushmaster. Only issue is that I'm having trouble getting it to fit over the gas block. I can get the rail to slide all the way down to the threads but it's just barely crooked enough that it won't thread. Any ideas? It's only too big on the bottom side and only by maybe an 1/8 inch- any reason why I can't grind it down slowly with a flapper wheel? Obviously I would shoot a spot of flat black paint on the bare metal so it wouldn't rust. What do you guys think?