it was a dry run. if you look at the column of ex army rangers proceeding single file up the steps, you see a very well trained militia. they didn't bring guns because the invasion of the capitol was a propaganda / psychological operation. to show marginal and sympathetic right wingers that this was all real, and happening, and to elicit a response from the government.

guns would have upped the ante on the core organizers and resulted in their decimation at the hands of local federal forces. This was just the beginning. from the angry anti government comments in this thread, their effort looks to be succeeding.