zimhunter
Do not confuse "double underlugs" with the "locking bolt".
Chapuis double SxS rifles have 2 parallel "hooks",[underlugs] one under each barrel, where typical double rifles have one "hook" in between the barrels. British, and most other doubles have 2 narrow "bites". The Chapuis has one WIDE "bite"[locking bolt]. Chapuis claims their system along with the design of the reciever is much stronger than the typical British style action.
I will say this, I have fired more than 2 thousand rounds through My 450 No2 [British] and my 9,3 Chapuis. Both are still tight on the face.
I have been told by someone who works on EVERY kind of double rifle that Chapuis are the best of the new made doubles, ie they have the least problems.
I consider my 9,3 Chapuis the best hunting rifle on the planet in its power catagory [medium bore].
In big bore doubles [40+ cal] I prefer British, but IF I was buying a new made double it would be a 470 Chapuis.