jimc
.223 Rem

The weapons that National Guard troops now carry in Washington, D.C.
The pistols and powerful rifles guard members carry are similar to those local police use across the country. Troops have been told to use their weapons only as a last resort.

"Armed guard members will carry the type of weapon they are normally issued and trained on, typically M17 handguns and M4 semiautomatic rifles, similar to assault-style rifles, the Defense Department officials said. Some guard members will carry M9 pistols."
"The military weapons are similar to those used by local police departments across the United States. The M4 is a standard semiautomatic rifle and has roughly the same capabilities as semiautomatic rifles used by law enforcement agencies."
I may be wrong, but isn't the M4 a select-fire rifle?