If you buy a 357 Sig, make sure you buy a 40 barrel for it. At least you can shoot it when ammo supply becomes an issue.
As far as SS using the round? Those guys could give a rat's ass for collateral damage for obvious resons. The Air Marshalls?
WTF?
The Secret Service is a LE agency just like any other fed LE agency, collateral damage is a concern for them as it is for anyone else.
Wouldn't look too nice to drill the bad guy and kill the Head of State of Whogivsashitz.
We'd probably end up writing an even BIGGER check than we were going to give them in the first place.
Bullet construction and velocity determines penetration. A bullet made to break up like a bomb will do so if pushed fast enough. If it's 'bonded' its still a bomb but will go a little deeper. Inside an aircraft is no different than a bus, train, or school. Dump enough energy and even if the round gets through, the likelyhood of it doing fatal damage goes way down.
The Air Marshalls are supposed to be at the pinnacle of handgun proficiency. Don't know for a fact, just read it somewhere.