Here's what it looks like when Marines blast their way into buildings while battling in cities

Lock buster 12 ga. or charges.

The modern emphasis on fighting in urban terrain started with the invasion of Panama. When Noriega's supporters holed up in buildings, US troops found themselves rather nonplussed about how to proceed. In one famous (in combat engineer circles) case, there was an exterior fire door on an apartment building, locked, and crouched in the hall behind it were about 40 of the local thugs ready to shoot to pieces whoever came through the door. The door was locked, and being a new problem, an engineer slapped 2.5 pound blocks of C-4 on each hinge and on the lock mechanism. When detonated, the charges sent the 200 pound steel, cement filled door down the hallway at over 100mph, spinning because of 2 charges on one side and only 1 on the other. As it hit the thugs, the bottom was slowed, so it became a large, heavy, spinning, tumbling chunk of steel and concrete which neutralized everyone in the hallway. In this case that was great, but what if it had been huddled refugees or a bunch of school kids? That is the incident that got the combat engineers, and in particular the Sapper School at Ft Leonard Wood, into the business of studying urban warfare operations. Studies which, I am sure, saved lives in the early days after the invasion of Iraq.

A lot of bang for the buck !