As for SCAR I don't know but as for WE M4..
http://wem4guide.wdfiles.com/local--...%20Diagram.jpg
Part 91
Its a nugget of clear rubbery plastic.
Why use a sorbo for that? Isn't recoil something that's actually desired for this gun?
Also how do you get in touch with tirador? haven't been able to contact the guy lately...