why is my moa changing HELP

[tjonh2001]

i am having some questions about my coyote rifle. i went out yesterday to test my data. i figured that i would have to make some changes. after shooting yesterday i made a drop chart for my 22-250 out to 600yards which was 11moa. today the i went out to shoot with a friend. we set steel targets at the same spot that i shot the day before, for some reason i only needed 9.5 moa. all that is different from yesterday to today is wind. yesterday wind was right to left at 14mph today 1mph left to right. does anyone have any ideas for me? is it because i am shooting a low bc bullet..
The rifle 22-250
700 bdl trued
26in shilen barrel
b@c tacical stock
mark 4 6.5x20 m1
mark 4 rings and bases
timney tigger
55gr vmax bc.255 3550fps

 

[devildoc]

What was the temperature difference? How bout barometric pressure? Are you sure your cheek weld and focus was set the same? It certainly isn't due to the bullet being low drag, as long as the same bullet and load was used for both sessions.

 

[tjonh2001]

when i shot yesterday it was 35 deg today it was 26 deg i cant figure out whats going on i checked my cheek by focusing the target in and moveing my head with out moving the gun. the crosshairs were solid. that is why this is so weird to me. i havent looked at my barametric pressure will that make a large difference?

 

[ss7mm]

i went out yesterday to test my data.

Is this new load/data or have you shot it before?

i figured that i would have to make some changes.

Why did you think that? Have you shot the exact same gun/load combo before at this same range, and if so, what data did you get then? Did you shoot steel both days or targets one day and steel the next? How precise was your aiming point each day?


Did you do, or have you done, any work on the gun??? Scope off, stock off etc.

Have you checked everything physically with the gun that might have changed? Action screws torqued right? Scope, rings, base all tight?

Did you shoot the same number of shots, in the same manner, per group both days? Did you use the same rest and shooting style/position both times?

If you have just the two days of data and believe there is a problem, then how do you know which day produced the most accurate data?

I guess what I'm getting at is check everything you can, make sure as much as possible is the same both times and remember that sometimes "stuff" happens. Copious field notes will tell you what you did, under what conditions, etc. every time you go out.

 

[Buffalobob]

In additiaon to what has been said, my guess would be that the 14 mph wind had some vertical components to it in additional to the lateral component. Wind is seldom completely flat and will swirl up and down particularly if there are hills and valleys or a tree line. Often times a shooting range wil have trees on one or both sides and this will change a lateral wind to an head or tail wind for a part of the distance.

 

[GSoD]

I'm not an expert by any means - but could some fouling have crept in? Or perhaps you heated up the barrel zeroing in and your shots the next day were a little colder?

Could be a 1000 things.

 

[tjonh2001]

it must be the wind caussing up and down drafts, i am shooting in the hills. today i took out my custom 7mm wsm and shot that and the data was changed about 1/2moa at extended ranges. this is shooting a 168 berger. it isnt affected like that little 55gr bullet. i think my 22-250 is bullet was at its max range. there were to many variables that i would have to account for. i shot both guns side by side the 22-250 was affected like before. i guess to make a clean 1 shot kill i will have to limit the 22-250 with that bullet to 500 yards and less. thanks for the help guys

 

[davewilson]

everything mentioned is certainly a possibility, but my guess would be the scope. i have a 6-20 on my Edge and had problems this fall with repeatability.Leupolds don't have the greatest reputation for repeatable tracking. i sent mine off to Cecil Tucker and got his coil spring/locking mechanism put on it. all i can say is it made one heck of a difference in mine.

 

[DIRTY 30 RUM]

I to have to agree that the Leupolds have trouble with holding zero, especially when adjusting MOA up and down. I have had two fail ,one on a RUM and the other on a WBY. I use a NXS on the RUMIE. With the R2 reticle I fly spot on. Zero @ 600 and use marks above from 0-500 yards. Any thing farther than 600 use the marks below the main cross hair. Now after 600 yards it starts dropping of the 2 MOA per 100 yards so you have two know your drop and bracket from there. This works for loads with .500 and above bc. 3300-3500 fps.