load testing?

[7.62_Reaper]

so i have been doing some load testing with the 338 LM. i have noticed that once the barrel heats up after the first 3 to 4 rounds the bullet will sharply drop 1 inch at 100 yards but will stay there consistently for the following rounds. is this a typical event thats happens to you as well after the bore heats up? i have had the same issue with my 7mm rem mag. i went back with both rifles and did a ladder test to make sure that the round was leaving the barrel at the top node thinking that it should help with the drastic drop in POI after the barrel heats up but it had little to no effect. after the barrel cools the rounds return to the original POI (with both rifles).

is this something that i will have to live with?…..its not i huge issue i have just been adjusting the scope for the new POI after i noticed the drop.

any thoughts?

 

[Dogtown]

This might help...

 

[zfastmalibu]

I would be interested in some chrono readings from those first shots. As I'm sure you have noticed during load development, groups print in different locations on target. At 100 yard velocity change does not cause this, it is caused by the harmonics of the barrel and where the muzzle is pointed when the bullet exits, not where the scope is pointed. You may be on the edge of a tune that is spitting that bullet low when the velocity gets up higher. You may find reducing the charge stops this or increasing the charge may keep all your shots at the other poi.