Re: Thumb Positioning
your discreption make perfect sense , I'm not sure that i agree with the statement that you don't want your thumb around the back of the grip. I realy don't see where it would matter where your thumb goes so long as your not pressuring the stock in any position. Some guns like to be choked to shoot well and other like to be free reoiled alot of this depends on the amount of recoil and torque the round produces also the shape of the stock and how it rides the bags.
I tried shooting my pet 308 that has a McMillan A-5 stock several differant ways including with the thumb on the same side as the index finger and as lonmg as I diden't stress the gun in any way it shot the same , typicaly my thumb rides strait up the back of the action inline with the bolt but behind it , this is a neutral position and most comfortable for me and now that i have a wide trigger shoe
(thanks Dave) I'm actualy in a little more comfortable position.
So inshort I guess I'd try and see what works best for you, but as a side note if your shooting a heavy recoiling gun pay close attention to your scope relation to your skull
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