Nah, it's just a seal Jonathan --- and a piss poor one at that. :-
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The cocking link has to bend like a banana on the 52/54/56 because the seal is so hard, my idea is to use a softer seal so the seal gives instead of the cocking link.
I can't think of another sliding breech gun that relies on the linkage bending to achieve an airtight seal.
The only downside I can think of to using a Weihrauch seal is a slight increase in lost volume.
I'll try to have a play tomorrow and get back to you --- unless Nick beats me to it.