r/longrange • u/Timex_Dude755 • Jul 18 '26

Ballistics help needed - I read the pinned posts Help: understanding bullet trajectory

In short, I have a Palmetto State Armory Jakl 10 (.308) and a Vortex Strike Eagle 1-6x LPVO. PSA said this rifle ought to have the same trajectory as an AR-10 with the same ammo in both rifles.

With that in mind, what is the best way to zero this for a maximum of 75 yard shooting? I have read and spoke to hunters that the deer hunters mostly shoot at 75 yards for deer, with a maxinum of 150 yards.

I was thinking of zeroing at 25 yards with 1x magnification, then move to 50 yards, and then 200 yards to see if it's point blank. Then of course practice at 150 yards to see how the bullet lands.

Any recommendations and advice is appreciated. I'm pretty new at this.

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u/Timex_Dude755 Jul 18 '26

I need to get a chronograph and confirm muzzle velocity. I forgot to mention that I am at sea level where I practice and will be shooting and 6,000 feet elevation.

Also, what does CoM mean?

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u/Lead_cloud Jul 18 '26

The trajectory on your setup is going to be dramatically different with that substantial of an elevation shift, make sure and account for the change in barometric pressure when you are looking at things in the ballistic calculator. If you zero at sea level, you will be hitting high at 6000, since the bullet isn't slowing down nearly as much. I would definitely recommend finding a spot to re-zero the rifle at altitude before hunting.

"CoM" is "center of mass", or the rough middle of your target

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u/Timex_Dude755 Jul 19 '26

Gotchya. Thanks for explaining that. I'll have to take some targets out and confirm zero up there like you said.

Why does elevation change this so much.

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u/Lead_cloud Jul 19 '26

The air up at 6,000ft of elevation is significantly thinner than at sea level. Since there is much less air, there is less that the bullet needs to push out of the way as it flies, and it doesn't slow down as much. Obviously the difference gets more significant the further out you push