enviromental coditions effecting bullet drop

[ven]

Was at the range today and went to my 500 yard target.PUt in 3.5 mils on my schmit and bender and shot a 3 shot groups it went lovely at 1.5 inches but was 2.5 inches high .
The other day 3.5 mils put me dead on now i need 3.4 is this normal at theses kinda ranges to be a click out sometimes and could this be the effect of the enviromental conditions .Thanks

 

[Willys46]

Temp?

My first ? would be temp. I have had it vary buy at least 1 moa form a hot day to a cold day.

Anther thing..Did you leave the ammo in the hot sun or in the car for a while allowing it to heat up? Some of the guys I shoot with during the summer months bring the ammo in a cooler.

But yes, envromental conditions will effect it that much. That is why it is important to get drop charts for different enviromental conditions or get Exbal and it will do it for you.

Willys

 

[Bravo 4]

I would agree with Willis on this one. If your ammo was left in the sun or in a hot chamber too long I think your groups would have been more erratic or have some vertical stringing. Are you using one of the extreme powders? They have a tendency to withstand temp changes better then most.

 

[ven]

Yes it was a warm day when my load was shooting a little high.

shot this morning very early when it was still cool and my rounds hit dead on at 500 .
Remembering back now it was an early morning that i made up my drop chart of my load.

Learning something new everyday.

 

[MontanaRifleman]

I ran a ballistics comparrison on the online ballistics calc I use @ 59 degrres and 0. Absolutley no diff. Not sure why and it doesn't sound quite right.

Another thing to consider is powder type. Some powders will change 2ft/sec per degree of temp change. I use temp stable powders.