Don't get me wrong, most of my readers who have military experience would probably refuse such an order, but you are the sort of military personnel who follow pro-gun blogs.
The military today is not comprised of the country boys who have set aside hunting rifles for military arms. It is comprised mostly of city denizens who haven't handled a firearm outside of military training. They don't necessarily see firearms as the right of the common citizen, and they don't imagine that everyone can be trusted with a firearm.
Add to that the fact that a person can volunteer for the military as a conscientious objector, and you really start to see the problem. Anyone who thinks violence is never necessary has trouble seeing defense as a right.
The founders saw the populace as the defenders of the country. When people say the founders couldn't have foreseen the future, they are right, but in the wrong way. Sure, they didn't know what technology would exist, but they didn't see a standing army, either. Technology would certainly keep progressing, they knew, but they didn't expect a standing army to amass all the power.
The really sad thing is, an armed populace is exactly the thing the founders thought would keep a standing army in check. We gave up the advantage, though, allowing the government to regulate away full-auto and the like. Now, the military has better equipment than we do.
If the military is asked to confiscate firearms, they may not have the experience to disagree with such an order, and they certainly have the technological advantage.
Whatever the case, though, we gun-owners have a numerical advantage. Remember that when anyone proposes a ban or other restriction.