Can't keep it on Target

[hylander]

My brother has a G-23:
First time out he was doing fairly well, keeping them all in a 6" circle at 10yds.
However this time out he is hitting mostly low and left, and some all over, alot not even on the paper 12"X12"
First off the Pistol and factory ammo are fine, I shot it and no problem grouping, it is him.
Second he does just fine with his 1911 .45, typical group for him is about 4"
Now he is using a proper two hand grip, Thumbs forward, this is new for him.
His old grip style was with one hand under the Pistol grip.
Any Pointers ? should he go back to the old way of holding the Pistol or
try to re-train with the new grip style.

[pinwheels]

Right handed shooter? Low and left? Glock? It's a flinch anticipating the trigger break. Make sure the gun is empty, get all the ammo in another room, put in a snap cap (or not). Find a safe area to point, and dry fire, watching the front sight. It shouldn't move. Lather, rinse, repeat. Weak hand should be 60% of the grip strength, and make sure the pad of the trigger finger is pressed straight back along the barrel axis. Too tight a grip with the strong hand links the trigger finger muscles with the grip and pushes the gun. A G23 freestyle is easily capable of 1-1/2" groups at 10 yards. Even I can do it.