DJ... don't know who made the cantilever set-up, but I saw it on 2 differeent SBE's... I'll ask my buddy who has one.
Stevenb... the one on the link looks better than the one I tried last season... it was junk (trashed my hunt) and scratched the receiver. I may order and try the one on the link you gave before going to a gunsmith.
I have a E.R. Shaw custom rifled slug barrel that is sweet, if not for that i wouldn't bother trying to mount a scope. I have my eye on a new SBE for next duck season and would like to dedicate the M1 as my deer gun until my son grows into it for ducks.
As for a gunsmith, the material thickness in the area at the top of the receiver seems mighty thin to tap into... especially since it's aluminum and would most likely require a helicoil insert, if they even make one that smal, even if they do you can only use a helicoil effectively once.
Thanks for the link.
Mark