Range Report .308 dope issue, what could be the cause.

[john_1182]

i have just got my new night force 5.5-22X50 MLR in high rev mounted it to me tikka T3 super varmint with the night force uni-mount using my previously developed load (lapua brass, cci primer, 47.5 varget, winchester power point seated to 2.85) average .75 inch @ 100 yards

this rifle and load has been out to 800 all the time and touched 1100 yards only thing to change is the scope

the issue. (all ranges confirmed using my LRF)

i have zeroed at 100 yards 4 rounds 1 hole in the steel target, but when i go to 422/ 555/ 647 and 742 yards all my rounds are landing .5 low (i know the data on the bullets is fine and bullet flight is fine as its the same rounds i was using before swapping the scope)

to fix this i have set my zero to 210 yards in bullet flight and every thing is fine, but at 100 i am shooting .5 mil high (have not had the chance to test 200 and 300 yards to see where it is landing).


what could be causing this ?

 

[Lindy]

Re: .308 dope issue, what could be the cause.

Slight differences in the elevation adjustments between the 2 scopes can cause this.

Believe the bullet.

But you can also check the scope adjustments: Optically Checking Rifle Scopes

 

[BryanLitz]

Re: .308 dope issue, what could be the cause.

Did you account for the difference in sight height between the two scopes?

Also, did you shoot all the ranges from the same position as you shot your 100 yard zero? For example, if you shot the 100 yard zero from a bench, then shot all the other ranges prone with a bi-pod, the difference in position might cause a different POI.

Just some thoughts.

Good luck.

-Bryan

 

[john_1182]

Re: .308 dope issue, what could be the cause.

all of the rounds have been shot from the same place same way, prone of bi-pod. as for the scope height, i didn't think of this..

just checked, both scopes have the same scope height, no issues there.

as for optically checking the scope i have not done this, as i assumed the tracking is not the issue as its constantly out buy .5 mil from 450 > 750 yardages.

only thing i can think is something might have happened when i was adjusting the zero stop after my 100 yard zero.. i would go check it in the next few days , but im fairly certain i will be getting my appendix out soon..

 

[john_1182]

Re: .308 dope issue, what could be the cause.

back again, sorry guys/ girls, i was in hospital for a few days, been out shooting again. had the same issues as described above, +0 mil was spot on but around +.5 mil and onwards would give me an extra .5 mil of elevation (tested up to 7 mil).

i seam to have worked out the problem by playing with the zero stop and re zeroing a few times, it looked like i may have been over tightening the zero stop screws on the NF scope.

i ended up doing a simple tracking test at 100 yards and all is now tracking well up to 7 mil ( max hold over with the MLR reticule) i will find out more in the next few days if the weather holds up