I have no experience with those guns, but if they show up as joysticks....
Control Panel>Hardware & Sound>Devices & Printers
Right click on it to go to controller settings, then properties for the input test, calibration and settings.
Calibration is under the settings tab.
Calibrate by pointing the gun along the edges of the monitor (and no further).
The next problem you will probably run into is that the gun is calibrated for a widescreen monitor, but the MAME play area is 4:3.
You could calibrate it to the 4:3 area, but then that screws up all the widescreen games.
Easiest solution is to just accept that the few games that can't be calibrated in-game will need to be played widescreen.
I suppose you could calibrate the gun in windows to the 4:3 area and then calibrate the widescreen games in-game, but that's kind of creating a problem for dozens of games to fix the problem on a few.
Also read up on analog settings in MAME as those will affect how well your guns will work.
from an old post about analog guns (in the Windows XP days when the joystick calibration was easy to find):
1. Calibrate the positional gun in windows by pointing it along the edges of the screen.
2. In mame.ini set the dead zone to zero.
3. In mame.ini set the saturation to 1 (100%)
4. Calibrate the gun in the game's service menu
5. Adjust the sensetivity under analogue controls in MAME's in-game menu until the crosshairs don't lag behind the gun movement.
(there is only ONE sensetivity setting, ignore all settings that include the word DIGITAL)