Mike
Not alot is said about shooting position and body support but for shooting handguns it is very critical. I have done a fair amount of shooting with handguns and long guns and have found that sitting at a shooting bench is not the most stable position for me. I susspect the reason is your upper body is not supported and can/does move around. Try this test, sit at a bench, put your gun in shooting position, holding just like you normally would, and have someone come over and push your shoulder sideways. You will see that you do not have alot of rigidness or control of your upper body. Does this contribute to our lack of ability to shoot good groups?? Maybe.
When possible I shoot off the hood of my truck with sand bags. I have found that by standing up with feet slightly spread and leaning into the truck with arms outstrecthed and resting on the hood my entire body is much more solid and I can shoot much better groups. Give it a try sometime, you may be surprised.
I like a loose grip on my Contender. The recoil does not seem as hard, the gun does not jump much or any more than with a tight grip, and it seems I am more consistent. With a tight grip I think there is more of a likelihood that we can/do move the gun slightly as the trigger is being pulled. If you shoot a bow, you know that a tight grip on a bow causes hand torque which is a death sentence to your accuracy. Not sure but the same may apply to handguns. Hope this helps.
Dave1