It's a guesstimate, you have to file down those indents, as seen in my guide, and yes it will look like a rip per say, but it'll function WAYYYY better than a AS one would ever do. Plus no tearing up a good AS stock.
NOPE!
You just file like 3mm on the sides of the indented part of the RS endcap. Then slide it on. WAYYYYYY easier than using a dremel on the airsoft version.