Re: TAILWINDS effect on group sizes????
A level tail wind will usually push the bullet up and then if it lets up, the bullet will go down and give you a vertical group. However, if you are shooting from under a roof, the wind accelerating over it can actually push a bullet down--hard. Up at my local range which sits at the mouth of a big canyon, the wind blows up the canyon after 10:00 am and the covered firing line faces slightly up the canyon so we get big time tail wind from 6 o'clock position or 5 o'clock. This wind races up over our slanted roof and once it gets to the other side it drops down from being accelerated exactly like a planes wing. This gives horrific vertical and the wind flags don't always show it because it is coming down at too steep of an angle. You just have to know it is there. One guy from Pheonix (I think) who was up here for a benchrest match took a smoke bomb, lit it, stood up on the corner bench and held the bomb up above the roof. You should have seen the smoke peel off the bomb and vertically circle down to the ground!
And remember, wind effects everything from an 18 wheeler to a jet liner to a 180 tx bullet. It will effect that bullet even more if it is slightly yawing when the hardest vertical wind hits which would be about 20 yards from the muzzle. In other words, all bullets yaw when exiting the muzzle but the longer the bullet, the longer it takes to quit yawing and it will be very sensitive to vertical wind during this period.
Try shooting out of the shed and away from anything behind you that might cause the wind to push down and see if your vertical improves.
You didn't mention problems with standard deviations in velocity so I assume your load is good and is only giving you vertical because of outside sources.
If it's not far, it's boring.