hey sorry was this very late response. My email isnt getting replies, not sure why yet..
The bonesteel arms fits like a GLOVE (like a really small glove)...
The Upper guard goes on similar to the stock VZ guard, however it has 4 fine strong screws which are used to tighten the upper guard into place (basically you tighten the screws with an adhesive causing them to be permanently in that position, therefore the upper guard wont move, allowing you to maintain a zero). The guard still comes on and off with typical ease despite the screw system. Its a smart way to make it work.
The Lower guard fits VERY TIGHT, but in a very good way (since you typically wouldnt be able to field strip it anyway). A couple hits with a rubber mallet does the job (couple meaning like 30), and its on for life. No dremel, etc needed.
Overall very impressive guard set. If you want more info on them, or a video of me removing the upper, I can supply one later.