It does an unbelievable amount of crit damage. In Concord, I managed to one-shot the Deathclaw with a critical to it's belly. I managed to two-shot the Mirelurk Queen at the Castle with 2 crit shots, at level 20. No Better Criticals perk, and only 2 points in Rifleman. Wasn't even Powerful Calibrated.
And the moment I collect the magazines, bobbleheads, and actually invest in Better Criticals, I'll be doing over 3 times that much crit damage...