Before I blame the scope....dope way off, any other avenues to chase

Hi guys,
New to long range shooting. I have done lots of shooting and deer hunting in the 50 to 350 range, but recently decided to get a 6.5 creedmoor bolt rifle to play with long range. The only other long range shooting I have done is at 1000 yards with a buddies .338LM, and it was like an easy button....we literally just guessed a velocity, entered it into a ballistic app (after watching magpul art of the precision rifle) and made hits. That was years ago and haven't done it since. My rifle is a 20" 10fcp-sr in 6.5 creedmoor, wears a silencerco hybrid (sounds amazing by the way), and a steiner t5xi 5-25 (with the upgrade), burris xtr rings with 20moa inserts, with a 20moa rail.

Anyways, I was shooting at 500 and 600 yards at my 12x20 silhouette the other day (the most I could get on this ranch, without having to hike up a mountain carrying my target), and my dope from both JBM and Shooter app showed me at 3.2 mils and 4.3 mils for 500/600 yards, yet I had to dial down to 2.7 and 3.8 mils to make center hits on the target. I am at around 4800 elevation, and it was around 98 degrees (I don't have the pleasure of a real range or anything, so I actually was laying on my mat, on a rocky road, in 100 degree weather to get the opportunity to shoot, put on long sleeve shirt so my elbows would stop burning on the mat) that day. When I change my normal inputs to the hot summer day input, it only subtracts .1 mils from each dope callout. Before I shot one of the arms on my chronograph, I averaged 2620 from my 20" barrel (without the suppressor, didn't get to chrono with it) with hornady black 140gr bthp (not sure if this is the same 140bthp listed in bullet libraries). I thought that might be the issue, increased velocity from the can, but it looks like I have to hit 2800 or so to make it match my dope. To make sure it wasn't mind games, I dialed to the dope in my app and would hit just below the target. Dialed back up and made center hits.

Any ideas to check before setting up box tests and all that? I don't have anywhere to shoot with a bench and real range to make that easy to do.

I could consistently make hits, center of my steel, holding .5 windage, and the previously mentioned dope.

Not ruling out a psychosis from the heat. Boy it gets hot in the desert.

Thanks for the advice for a new guy.

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Originally Posted by johnnyrebel87

....my dope from both JBM and Shooter app showed me at 3.2 mils and 4.3 mils for 500/600 yards, yet I had to dial down to 2.7 and 3.8 mils to make center hits on the target

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Originally Posted by johnnyrebel87

To make sure it wasn't mind games, I dialed to the dope in my app and would hit just below the target. Dialed back up and made center hits.

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I pulled those two lines out of your post because they contradict each other.

If you're 0.5 mil off at multiple distances, then you should re-check your 100 yard zero (or whatever zero you're using as the basis for your ballistic calculator).

If your zero is good, then switch to using hold-overs instead of dialing to rule out an issue with the elevation adjustment of the scope. This will help narrow things down.

I'm no expert at this stuff, but if you get into the settings on your ap your using, you can tweak the entered velocity to come up with true numbers that your rifle/load are doing. I "trued" mine by shooting at clay pidgeons at 600 and 700 yards. Dont worry about hitting them, your looking for bullet drop to get on. Adjust scope accordingly , make note of the elevation, then tweak the velocity on the ap to get as close as possible. Then confirm at various distances. This is how I got dope for my 308.

Thanks guys. I had zeroed right before taking it out. Next time I go out, I will try some holdovers.

I will check my notes and see what was going on, I think I misspoke, I meant shooting over. I confused my misses in the wind for shooting under (due to the dust that fli3s up).

Maybe when I set my turret back to zero, it changed? I thought it would click if that happened, though...
And a whole half of a mil sure is a lot of clicks.


I appreciate the info guys. I will confirm my zero before doing anything else, and then try holdovers.

If you don't have access to another chronograph, be careful with adjusting the velocity in your calculator to try to fit your dope. For instance, if you're 0.5 mil high on multiple targets from 200 to 800 yards, then your velocity is probably close to actual, and you only need to re-check your zero. If you put a much faster velocity in to compensate for the 0.5 mil, the calculated trajectory will diverge from the actual trajectory. This means you'll be on target at the one distance where you fudged the velocity to meet your dope, but at other distances it will be off, especially the further out you go.

In both JBM and Shooter did you enter your altitude above sea level and temperature to correct for density altitude?

Check your scope height above bore.

Sent from my XT1565 using Tapatalk

Must be a zero issue, that makes sense.


Height above bore and elevation and temperature are correct. Even at the extremes of these variables, there was only .1 difference from what I saw.

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Originally Posted by johnnyrebel87

Must be a zero issue, that makes sense.


Height above bore and elevation and temperature are correct. Even at the extremes of these variables, there was only .1 difference from what I saw.

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A lot of good advise given already. My first thought was check your zero as is already stated. I have encountered this problem so many times I can't count. I have multiple boxes of 300WM and 308 loaded and going from one to box to another can be .5 mil different based on powders. Also going from hot weather to Cold, from Ammo baking in the sun....the list is long.

I try to poke one round at 100 before I start slinging long range. But Ive skipped the step too many times to count, only to go back to my 100 near0.

PB