how much do your crosshairs move?
Can you hold them on a 1/4 inch spot while breakgin the shot?
This spoke to me. I've recently started dry firing 2-3 times while letting the barrel cool. I find that when the firing pin drops, my crosshairs DO move, more than 1/4-inch. I don't think it's a flinch on my part (though it could be, I suppose) as much as the spring and firing pin movement within a relatively lightweight rifle. I'm guessing this could be a real detriment to my efforts for nice groups. Am I right?
We all think we are good if we can hold fairly still. Even when a bolt gun pin drops their can be stress induced movemtn... if its moving without a round, its moving while the bullet is in the barrel too...
Dry firing can show a LOT of things that you normally don't see because its masked by recoil.
I have not benched an AR in quite some time, but as I recall I never got totally rid of movement, but there was not enough movement to move me off a 1/4 inch dot.
Parallax can kill you as mentioned BUT IF you do things right and the same you can not have it present even without adjusting.
Mirage can open groups beyond what you believe. Wind adds to that(2 seperate things for sure) Shooting at night with no mirage, and no wind and having zero parallax will show better groups than during the day usually...
Getting the position repeatable, comfortable, relaxed and solid, how ever you go about it, is what you are after.
I wrap my off arm around the rear bag and pistol grip often, to get comfortable.
I want my chest touching the bench in 2 spots, not one large flat one.
I shoot better with my firing arm elbow on a small sandbag...
Just some of the things that help me...
