Would you use a big bore rifle to clear a room?  A .50 Beowulf by Alexander Arms was used, with a follow up by a 1911 in 45acp, at this fun shoot.

Tarded. That 1911 could flatten the whole building in 1 shot with it's mighty 45.

Seriously, room clearing has been done with bolt guns but probably not the most effective way. A 10 round box mag on a Barrett would be devistating inside of a house. 1 shot would literally deafen everyone in the house.

With that said, I'd use a barrett 50 shove it thru a side window, let off all 10 rounds inside the house. Then stroll through the front door with muh 1911.

Mosin nagant with bayonet is the only way to clear a room.

M91/30 or the m38 or m44?

m44

Cool.  

.50 BMG because everyone knows just the concussion will kill everyone in there.