Quote:
certainly stronger tha the top lever.

How does it add strength, it simply holds the bbls shut? When a shotgun action fails it is most often from cracking across the juncture of standing breech & Bar. Neither the Jones nor the "Purdey" double underbolt provides any additional strength to this area whether the later be actuated by a thumb push or top lever.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra