Conduct your own tests like Metal God did.
Metal God's data is a five shot string, not something I view as conclusive, nor have you provided data supporting this theory of yours. I have been shooting over a chronograph since I first bought one, which would have been back in the late 80's, early nineties. I have shot tens of thousands of rounds over my chronograph and I have not seen velocity varying by how tight or loose I hold my firearms.
If anything is affected by recoil, most certainly a handgun would be. and just this week, I was shooting over a chronograph with a M1911. Sometimes one handed, sometimes two handed. I have not seen anything to verify your theory and since this is an extraordinary claim, you need to show some extraordinary proof.
As for chronograph use, I think you Bart Button, were a very active shooter, but not anymore. I am an active competitor, shoot with active competitor's, a couple of whom are F Class National Champions, one sling shooter on the US Shooting Team, I think also the Palma Team. Last weekend I was shooting with my Palma friend and he is very aware of the velocity of his bullets and the speed at which his and his bud's 155's are going. This is a very important data point to all those using the 155's. My F Class National Champ bud, who has won F TR and F Open, I occasionally meet him at the range testing over a chronograph. My friend has set National Records, unlike your
almost National record in Smallbore Prone. This is something you regularly trot out to impress those who, presumably, are impressed by someone who was
almost famous by
almost setting a National Record. My bud is a extreme experimenter, I have held his data books where he has tested primer/case/bullet/powder combinations for velocity, accuracy and consistency. Maybe that is why he is a multiple National Champ and you on the web telling all how you were
almost famous.