Help- I'm new to scope dialing and am a little perplexed at initial results.

[MOJO67]

Gent's

This is my first foray into scope dialing, so please go easy on me. Anyway, I just installed a Nightforce SHV on my Tikka T3X 6.5 Creedmoor. After getting it sighted in, zeroing at 100, verifying accuracy and velocity of my pet load(147 ELD-M), I plugged the data into my Ballistic App. Initially, it appeared to be spot on, as my elevation impact was right on the money at 200,300 and 400 yards. When I dialed for 500 though, the bullets were impacting about 6-7 inches high? Any idea why this happend? I feel like all my inputs are correct, especially since drops at 2,3 and 400 yds were right on the money.

Thanks all. Any input would be greatly appreciated.

 

[LaHunter]

My first guess would be that the scope elevation dial is not functioning properly, since you were "right on" out to 400 yards dialing. I know people swear by Nightforce scopes, but any brand scope can have a defective item occasionally.

 

[The Oregonian]

To add on, that can be verified by doing a box test at 100 yds. Or if you just wanted to check elevation you could just dial your so,unions for 200-500 yds and measure impact compared to zero.

 

[xdHammar]

Did you set the altitude in your ballistics app? How did you confirm velocity? Do you know for sure its 500 yards? It doesn't surprise me that you were on at 100-400y, it's over 500 that things get interesting.

But like LaHunter said it might be the scope tracking. Every scope should be checked regardless of brand and price.

 

[gohring3006]

Double check your inputs.

 

[entoptics]

For a 147 ELD-M I get the following.

2600 FPS
(yd) (in) (MOA)
200 -3.9 -1.9
300 -14.0 -4.5
400 -31.0 -7.4
500 -55.6 -10.6

2700 FPS
(yd) (in) (MOA)
200 -3.5 -1.7
300 -12.7 -4.1
400 -28.3 -6.8
500 -50.9 -9.7


2800 fps
(yd) (in) (MOA)
200 -3.1 -1.5
300 -11.6 -3.7
400 -25.9 -6.2
500 -46.6 -8.9

Assuming 1/4 MOA clicking turrets, there's only 7 clicks difference at 500 yds over a 200 FPS spread. At 400, it's about 5 clicks, so it seems like 5-6 inches at 500 yds would have shown up at 400 yds if your inputs were wrong. That being said, it's also really hard to believe ANY scope above "airsoft" price would be off 10-20% with it's tracking at less than one revolution on the turret, let alone a NightForce.

I'm a data snob, so I have to ask. How many groups did you shoot at each distance? Could it have been a fluke result? If it was only one group, then I'd be inclined to chalk it up to a loose nut on the trigger...

As mentioned though, the best thing to do is try and reproduce the problem under controlled conditions. Do a "box test" on your scope, and if that passes, shoot a couple of groups at each distance, being absolutely anal about calculating and clicking, to ensure it wasn't just a brain fart or weird fluke.

 

[the hunter]

1 check scope 2 check your ammo, there have been reports of hornady eld-m blowing up past 400yd. I dumped the 140s in my 6.5cm after it giving me .5 moa at 100yd and then shooting 1.5" at 100yd. I swiched to federal gold metal match with 130gr berger HOT, and now I git .5 moa every time I shoot with it.

 

[Buckfever34]

Did the barrel get hot?

 

[MOJO67]

Thanks for the input.

I sure hope it's not my scope. Went the NF route hoping to avoid these type of issues. Guess I need to look into how to perform a box test.

As for checking velocity, I used my pro chronograph and ran appx 10 shots across it when sighting in at 100 and took the avg, which was right about 2600 fps. In regard to inputs, I put all the basics(sight height, alt, pressure, temp, velocity, bullet weight, BC, etc. After the output was generated, I utilized the data to shoot 3 shot groups at 200,300,400 and 500 yards. This is where I discovered the discrepancy at 500. The barrel is relatively new and only had 25 rounds through it when I started the test. Although, it was clean when I started my test, maybe by the time I went out to 500 it was fouled bad enough to create the high impacts??

Regarding the data I was using. My Ballistic App showed I would have -58.63 inches or 11.20 MOA of drop at 500. Sorry for the stupid question, but wouldn't this equate to 56 clicks up on my elevation turret(which is what I used)? Below is the ballistic chart I utilized based on my data.

Thanks again everyone.

 

[stx]

1 check scope 2 check your ammo, there have been reports of hornady eld-m blowing up past 400yd. I dumped the 140s in my 6.5cm after it giving me .5 moa at 100yd and then shooting 1.5" at 100yd. I swiched to federal gold metal match with 130gr berger HOT, and now I git .5 moa every time I shoot with it.

ELDMs in my CM have been consistent.....all the way out the 1300 yds.

 

[BW64]

I put your info in my ballistic calculator & came up with 53 in of drop at 500. What ballistic app are you using? Does it ask for BC? Just a thought.

BW

 

[Muddyboots]

Are you sure about your Sight Height of being only 1". That can skew your BC calculator easily at longer ranges.

 

[Buckfever34]

Also, verify your sight height....

ETA: just saw the post above

 

[06mauser]

Assuming your scope is 1/4 moa clicks, if you dialed 56 clicks that would be equal to 14 moa not the 11.2 moa that you drop chart shows. But I may be reading this all wrong.