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>>Pete, here's the rib your patent refers to. If you press the button, the rib can be pulled toward the muzzle and off of the gun. Daryl<<


This wasn't for what I was searching but it is a removable piece.

https://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=60372&page=7
(one page forward)

Maybe it was Emil Flues SBT, but German made??

Serbus,

Raimey
rse