Someone to Talk

[Sasquatch the Reaper]

By that, I meant, say a person normally carried a PDW 5.56, but then had to go on a mission.

Could that person feasibly have a second upper that they could swap out on at HQ, go into battle with the upper (It would go from a 10.5 inch barrel to a 14.5 inch barrel), then later on come back and put the PDW upper back on?

Or does it make more sense to just have two separate weapons?