Thumb position

[stokesrj]

The Army Marksmanship Unit teaches laying the thumb natrually along the left side or the rest and a semi firm grip similar to a hand shake. They also teach that it isn't important where your finger contacts the trigger as long as it can be pulled straight back with no side torque. You can easily see if you are doing this or not by dryfireing while watching your sights. If they don't move then you are performing proper trigger control.

Some bolt rifle are set up for thumb to the right but this is for speed during the rapid fire stages, not precision trigger control. The most famous prone stock, the McMillan Anshutz has a thumb rest slightly to the right of center which places the thumb almost upright.

Here is a video of Garry Ellisseo shooting one of his tube guns with his thumb to the right. http://www.youtube.com/watch?v=rw7nkHAGD...ure=fvwrel
Most people shooting a Tubb 2K shoot with the tumb on the left because it is set up to work the bolt more ergenomically and can make the time limits during rapdid fire doing so.

Some benchrest shooters don't even use the grip, instead, they pinch the trigger between the thumb and trigger finger with the thumb behind the trigger guard. http://www.vintagebenchrest.com/page19/f...ge19_1.jpg