I have a gen 2, and yes had a couple of the pin holes that were tight. I filed off the anodizing inside the holes which did the trick. I realize people might be upset at having to do this on an expensive part, but overall I'm really happy with the kit. Had a problem getting the pin out of the recoil buffer holder and ended up breaking it (the holder, not the pin,stupid mistake) but Wolverine had one in stock which got me going again. The ergonomics are good with the ACR stock and a slightly lower rail. And yes, this is obviously an expensive proposition to build an SL8 but I like mine a lot and am happy with the end result.