Posted: 1/11/2026 1:32:32 AM EDT
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Ok, so I need to set up a rifle for a specific range using stuff I have, and I need a reality check by those who know. The rifle is a 24" and has 20moa built in to the rail. The ammo/caliber is 6.5 Creedmoor using 140 gr match ammo between 2700 and 2800 (I have Hornady and Black Hills (Berger bullets)). The scope I need to use is is a Vortex Golden Eagle 15-60 (55 MOA Vertical adjustment). The RANGE I will be shooting at STARTS at 600 and goes to 1200 and I will have to DIAL the scope. I have 0 MOA rings right now (net 20MOA) OR I also have a 30 MOA one piece mount available. Rough back of the napkin math seems to indicate I am going to need ~28 MOA adjustment between 600 and 1200 (if I figured things right.) Depending on how far my 600 yard zero is away from mechanically centered my MAIN worry is if I am zeroed at 600, I could run out of adjustment by the time I get to 1200. If I switch to the 30moa mount (net 50 MOA), then my 600 zero should be close to the bottom of the adjustment range of the Vortex scope which gives me plenty of overhead when I go from 600 to 1200. The other reason I am posting here discussing this I only have a 100 (near my house) and 200-600 (Hour and a half away) yard ranges to zero, verify and practice, and I need to prepare in such a way that when I show up at the 600-1200 (two and a half hours away, with no access until the day.) 100% ready to go. So, I ALSO need to calculate the offset of how far above the Point of aim my shots will have to be at 100-200 to end up zeroed at 600. I am pretty sure I won't be able to actually zero at 100-200 because of all of the MOA I am adding to get to the 600-1200. Caveat(s): Yes, I know other calibers/scopes/ammo whatever are probably better for this, but this is what I have. I know I should actually verify at 600-1200, but I simply do not have access to anything farther than 100 (local) and 600 (with effort.) Yes, I know I have to practice more, and I do intend to do that. |
You got gun law problems, I feel bad for you son. I got 99 problems but a ban ain't one. -Sylvan
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Using my data for 6.5 Creedmoor with a 140gr Aeromatch (Berger hybrid clone) going 2740fps at 70 degrees, 50 percent humidity and my barometric pressure 26.26 inhg. With a 100 yard zero, for a 600 yard shot you would need to dial up 12.5 MOA, for a 1200 yard shot you need to dial up 38.75 MOA. I live at 4200 feet above sea level so depending on where you live and your barometric pressure it will change the amount you need to go up quite a bit. With my data the bullet would still be going 1385 fps and well above being transonic so 1200 yards is a very doable shot. I shoot at 1115 yards regularly so 1200 in 6.5 Creedmoor is challenging but within the calibers ability. This was calculated using AB Quantum with their custom drag curves. |
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Here OP, just fill in your info... https://www.jbmballistics.com/cgi-bin/jbmtraj_drift-5.1.cgi |
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Originally Posted By jbirdious: You can and should zero at 100 and will have plenty to get to 1200. No, mathematically if I zero at 100 I won't have enough elevation left in the scope to get all the way out to 1200, especially because I'm supposed to dial all of the elevation, I'm not supposed to be using any bullet drop or reticle compensation. I like the JDM, but I have streloc on my phone to use on the range because I don't really have service. Thanks chocolate, I'm a lot closer to sea level than you are, maybe only five or six hundred feet, and it's also going to be a lot warmer, at the earliest well into spring before I'm actually shooting. So I'm pretty sure I'm on the right track as far as how many MLA will put me in the ranch where I can adjust as much as I need to adjust. If I'm not mistaken 50 MOA should put my 600 zero at the bottom of the mechanical adjustment of the scope which means I should have the maximum amount of elevation left. |
You got gun law problems, I feel bad for you son. I got 99 problems but a ban ain't one. -Sylvan
| If I’m understanding correctly, your rifle has a 20 MOA rail in its stock configuration. Your scope has a total of 55 MOA vertical adjustment. Assume your rifle had a zero MOA rail and you zeroed at 100 yards, that should put you close to the middle of the scope adjustment range leaving you with about 27.5 MOA of vertical adjustment. With the 20 MOA rail you should have around 47.5 MOA of vertical upward adjustment and 7.5 MOA of unusable downward adjustment. You should be able to zero at 100 yards and have plenty of adjustment to get out to 1200 yards. |
Do a tall target test at 50 yards. To go from a 100 yard zero to 1200 yards you need about 44min. You said the scope has 55 min of elevation adjustment and you have a 20 MOA rail. I think you will be just fine with a 20moa base.  These are approximations based on my numbers but at 50 yards: A 100 yard zero is going to be - .75" (below your aiming point) A 600 yard zero is going to be + 6" A 1000 yard zero is going to be + 15.5" A 1200 yard zero is going to be + 22" A tall target test will also tell you if there is any windage error built into your system. |
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Originally Posted By bpm990d: Do a tall target test at 50 yards. To go from a 100 yard zero to 1200 yards you need about 44min. You said the scope has 55 min of elevation adjustment and you have a 20 MOA rail. I think you will be just fine with a 20moa base. https://www.ar15.com/media/mediaFiles/98564/25yd85x14copy-3693084.jpg These are approximations based on my numbers but at 50 yards: A 100 yard zero is going to be - .75" (below your aiming point) A 600 yard zero is going to be + 6" A 1000 yard zero is going to be + 15.5" A 1200 yard zero is going to be + 22" A tall target test will also tell you if there is any windage error built into your system. A great idea for him to work out if he has enough adjustment, also bonus for making sure scope id installed and working right as well..OP might add a box test as well, it covers windage and makes sure the scope is moving the right amount to match what you think you are dialing..I combine both, you need to be accurate on your measurements and markings including making sure you are exactly 100 yards from muzzle to target... The 5-10-15-20 represent 5 MOA... which is 5 x 1.047" at 100 yards ...Both elevation and windage... Attached File |