To round out this squad, I also magnetized the heavy weapon marine. This time I magnetized both arms so I could let him carry the missile launcher and the heavy bolter, which utilize different left arms.
I considered magnetizing the backpack, but opted not to for simplicity, and to give it a bit of a different look when he's got the heavy bolter.
Alternately, you could equip the marine with magnetized pistols and close combat weapons of any variety to create an ad hoc squad leader for times you want to select smaller 5 man teams. At this time, I've not built any other Sgt. upgrade arms to demonstrate, but will be looking at that as a future upgrade.
In the future, I'll discuss how I magnetized the miniatures to allow for greatest compatibility, and thus flexibility. Stay tuned!