ericbc7
Well-Known Member
I bought a new "old stock" 7mm Tikka and set it up for deer season at the last minute.
I sighted it in at 100 yds with federal 150 gr ammo and tested it at 461 yds on steel, translating to 25 clicks on my Athelon mrad scope. Temp was about 50 degrees or more (ammo was warm from cabin). After 2 days of hunting with rifle and ammo in truck (so ambient temp) I decided to check my zero on the 461 yd target with temps at 7 deg f.
First shot missed steel entirely, I had to add 5 clicks to the elevation to get back on target. Using StrelokPro pro and by experimenting with inputting lower velocities I estimate I lost over 300 FPS due presumably to temp change. I assume this will vary depending on powder type or brand of ammo.
the takeaway is don't assume your drop charts apply when weather changes dramatically. Btw, it got down to -3f but I didn't check zero due to time constraints.
I sighted it in at 100 yds with federal 150 gr ammo and tested it at 461 yds on steel, translating to 25 clicks on my Athelon mrad scope. Temp was about 50 degrees or more (ammo was warm from cabin). After 2 days of hunting with rifle and ammo in truck (so ambient temp) I decided to check my zero on the 461 yd target with temps at 7 deg f.
First shot missed steel entirely, I had to add 5 clicks to the elevation to get back on target. Using StrelokPro pro and by experimenting with inputting lower velocities I estimate I lost over 300 FPS due presumably to temp change. I assume this will vary depending on powder type or brand of ammo.
the takeaway is don't assume your drop charts apply when weather changes dramatically. Btw, it got down to -3f but I didn't check zero due to time constraints.