let security officers swap their guns at secvends

[Kotlol]

Oh, no, you do not need a "one of each" in your team, and your absolutely shouldn't force someone to take one gun over another just for the sake variety. It might happen that an officer is only familiar/likes X gun and will do badly with any other.
Whilst a good sec team can do wonders, a good sec team does not need to have "one of each" in the arsenal. Consider that an actually robust officer can deal with 90% of the threats with a couple of flashes and some fire extinguisher and that whilst tasers are a great addition to your gear, they are not a win condition or anything like that.

Not saying you should, but just to point out OP's mistake that if you want to swap your guns.. just have everyone pick one. It's that simple.

HELLA NO DO I SAY EVERYONE MUST TAKE A DIFFERENT GUN!
I am just saying "IF"