Calibrated Receivers and, presumably, Photon Capacitors double crit damage.
I've seen this reported in a couple forum threads, including one from Reddit with actual research by a user called "jacknbox".
They tested crits on survival difficulty versus an enemy with zero damage resistance. They used a combat rifle, and compared the Calibrated Powerful Receiver to the .308 Receiver. They also did some tests with and without the Rifleman and Better Criticals perk. Those extra perk tests aren't really relevant to this question, so I've omitted them. The numbers below are without these perks.
Here are their results:
Calibrated Powerful Receiver
- Listed damage: 49
- Non-crit: 24.5
- Crit: 98
- Listed damage: 57
- Non-crit: 28.5
- Crit: 57
They're playing on survival, so the actual, normal damage is cut in half from what's listed in the Pip-Boy. That's why you see the calibrated powerful receiver's actual damage at 24.5, which is half of 49.
Note that the .308 receiver's crit damage is twice the normal damage (57 = 2 x 28.5). Compare this to the calibrated powerful receiver's crit damage, which is four times the normal damage (98 = 4 x 24.5). Four times is twice as much as two times, so the calibrated receiver doubled the crit damage compared to what it would have been otherwise.
You get more crit damage with the calibrated receiver than with the corresponding damage receiver.
Returning to the 10mm Pistol as an example, the Hardened Receiver only adds 5 damage. This is much less than would be required to double the gun's damage, which is what would be required in order for the crit to be as damaging as with the calibrated receiver.