Well, you could have one the modern day warior using the USP as a sidearm and the other as the 'old school' vet that keeps the 1911 close by.
Gives you an avenue for dialogue between the two...
+1! By doing this you give each character their own distinctive personality. This could give some conversation at some point. I like the idea of the Modern Day Warrior and the 'old school' vet having a conversation like this:
*The old school (OS) vet is cleaning his Colt Government model 1911A1 with a cloth, the Modern Day Warrior (MDW) notices his choice of sidearm*
MDW - HAHA, you gotta be kidding me, you might as well be cleaning a sharpened stick.
OS - Watch yourself son, this is a Colt Government Model 1911A1, greatest handgun ever made.
MDW - You really think your Colt
is as good as good as my HK?
OS - Better.
MDW - My grandfather used one of those!
OS - Smart Man.
MDW - My HK can carry 12 +1 in the chamber, you can carry 8 rounds at best!
OS - I won't waste rounds then, will I?
MDW - Why on earth would you consider carrying that obsolete piece of crap around?
*OS looks up from cleaning his 1911*
OS - Because how many Nazis did your HK kill?
MDW - ....