You can conceal anything with the right holster pants and shirt. I am a small guy and easily conceal a 5" standard 1911, or my Walther PPQ 4" .40.
Like others said, it is the weight and grip size that makes things difficult to carry concealed. I conceal the 1911 better than the Walther so I usually carry it, the weight does not bother me but i need to get a better belt and holster.
I am 5'6" 140lbs nekked with a upper torso that is wider in all directions than my waist, so with a loose fitting shirt that drapes off of my shoulders, hiding these large pistols is not an issue at all