Question for the long range shooters

[Korhil78]

I have been shooting the 115 gr bergers for the 25-06 and got the group down to under a 1/2 in at 100 yards but when I go to 200, 300, 400 and back..it jumps up to MOA or a little larger. I have the bullets seated right at the lands. Should I start backing it off of the lands and shoot them at 200 yards and see how they do or what? If so, what increment should I be backing them off at?

Thanks

 

[Greyfox]

I don't think seating depth is your issue. I have had the opposite issue where my groups are larger at 100 yards than at the longer distances. This is typically attributable to bullet stabilization. I don't think changing seating depth will fix your problem. I would look elsewhere before I would change a load that groups .5 MOA at 100. Some questions would be:
Is scope parallax properly adjusted?
Reticle/target relationship optimized for .5 MOA shooting at longer ranges?
Wind/ mirage conditions effecting longer range shooting. This is typically what causes me to have the problem you describe.
Is your barrel twist rate matched to your bullet?
Is the barrel condition the same when you shoot long range( temperature, cleanliness)?

If you were to optimize seating depth, changing in .025" increments until you get your tightest group. You could then fine tune if necessary. This is done at 100 yards so other variables like wind and mirage don't skew your results. As mentioned, your
load seems ok if it is consistent at 100 yards and your twist rate is matched to the bullet.
Hope this helps.

 

[Korhil78]

Wind/ mirage conditions effecting longer range shooting. This is typically what causes me to have the problem you describe.
QUOTE]

That was what was happening. We shoot at the base of a mountain and the range goes all the way out to 800 yards. Well where I was shooting from it wasn't windy but at the backstop it was windy. I guess the wind does weird things around the mountain. i just couldn't tell because there is not a wind indicator set up.

thanks.

 

[WildRose]

Wind/ mirage conditions effecting longer range shooting. This is typically what causes me to have the problem you describe.

That was what was happening. We shoot at the base of a mountain and the range goes all the way out to 800 yards. Well where I was shooting from it wasn't windy but at the backstop it was windy. I guess the wind does weird things around the mountain. i just couldn't tell because there is not a wind indicator set up.

thanks.

Wind follows terrain and then you also have to deal with pressure variances and up/down drafts which makes mountain and coulee shooting much more challenging than flatland.

Study the foliage and dust swirls and it will tell you where the directions and velocities change.

There's no way to plug all of those variables into a formula but with practice you can learn to dope it accordingly by "feel".

Southern NM, Western ID and SE Montana can get really challenging for the above reasons.