how different rests affect grouping

dont rest your barrel on the wood contraption. By resting the barrel on your rest the barrel harmonics are changed. Get some actual sand bags, I made some out of old lead shot bags. Rest the fore arm on the sand bags, then you will find the true grouping of the rifle. You want NO weight on the barrel, not even your hands.

Many people anticipate the shot and relax their grip right when pulling the trigger, which drops the muzzle for the shot. That potentially could explain your lower groups, if the towels let the gun lower but the wooden rest does not.

What DuckinDawg said. Shot bag size bags with kitty litter. Sand is too heavy, although I use three kitty litter and one sand. The sand goes under the forearm.
You can easily influence the barrel harmonics. They really do vibrate/move. Shoot one round at the bull. Hang a sand bag from the barrel close to the muzzle. Same difference. 'Course we could get into changing recoil but hey its a 22.
That IS water, isn't it?

"During firing, the chamber pressure rises from atmospheric pressure to, in a typical rifle cartridge, pressures of about 50,000 psi within milliseconds. This rapid increase in pressure causes the barrel to vibrate at a certain natural frequency, much like a tuning fork. The point in time at which the bullet exits the barrel will determine the orientation of the muzzle relative to its rest position. Exiting near a peak or valley in the motion means the muzzle is relatively stationary, and shot dispersion will be minimized; exiting between a peak and valley means the muzzle is rapidly moving, and shot dispersion will be greater.[44]

There are two ways to address harmonics; reducing the amplitude with a stiffer barrel, or working with the natural frequency to minimize dispersion."

OR, the best way to shoot your rifle is rest the forearm evry time. For utmost accuracy, that is.

Do you think it's possible that when you change the way the rifle sits, that it inadvertently changes the way you hold it? It could be very minimal nuances that affect the grouping.

I just know that for me, at some angles and whatnot, I don't get to hold it precisely the way I prefer due to outside forces.

That chrony is a lot closer than I would have placed it. Do you use it at the muzzle like that?

I shoot better with sand bags or a more formal rest such as available from Caldwell. In particular I use "The Rock" for rimfire rifle shooting and sand bags on the rear for support. There are better rests around. Always rest the forearm on the rest and have the barrel not touching anything. Don't apply downward pressure with your hand on the forearm when shooting. This keeps you consistant in your shooting. Try to have your rifle pretty much right on target while sitting free on the rest. Then you just adjust slightly and shoot.

Are your groups improving?