Ok----Have a think about it

Meteors have hollowish breech jaws and the front stock screw brackets below the jaws --and have a problem with the jaws opening up.

Mercurys have more solid jaws and the stock screw bracket is not on the jaws. However later Mercurys have a bolt barrel pivot ----------so that must be because of a problem.

Weihrauch knew they had a problem so they just fitted the bolt from the start.

Cadets and Majors don't have the problem because they are either better designed or better built!