Garands can be loud. Someone did something about that.
In this vid you can better hear the difference twixt suppressed and unsuppressed Garands
Fitting a suppressor to any semi-auto can be tricky. In this case there's a lot of blowback (hence wearing ski goggles when firing) and an adjustable gas cylinder lock screw to get the right amount of pressure in the gas system. In a thread on this build it's mentioned that the point of impact was about 27 MOA lower with the suppressor on. Details of how this was built can be found here.