The new bomb fuzing needs to be an option.

[Letum]

Originally Posted by Tbag

It took me some time to figure it out but I think thats what he means with "the casing doesn't matter, it's all about the detonator". I'm sure he will clarify soon.

Hmm...if his point is that impacts to the casing won't cause detonation after the bomb is armed, he is wrong. that's how I read it anyway.
If his point is that the arming vane will continue to arm the bomb after the bomb takes impacts that don't damage the vane, he is right.

It was making this and being in the DBS that got me interested in US bombs.

You can see part of the rear fuze there. The vane is on a long spindle so that it isn't in the dead air directly behind the bomb.
The rear fuze is both a back up, in case of failure of the front and also because time delay fuzes where fitted to the rear fuze only to protect the time delay from impact damage.