I have a Tikka CTR 308. I switched ammo to a Nosler 165grain Accubond. After 3 shots I was zeroed at 200 yards. Shot 4 another bullseye. The conditions are 85 degrees 70% humidity, 7-10 mph wind directly into my face and I am shooting off sandbags.

Let's go to to 300 yards.
My Ballistic app says I should be at .7 Mils, (7.6 inches)

First 2 shots 15-16 inches low with .7 mil adjustment. I thought I must have taken bad shots.

Shots 3-4 still way low. Make adjustments.

Shots 5-6. 1.5 mil adjustments with wind gusting a little stronger in my face. And I am still low.

Any suggestions, ideas or information on why this much adjustments?

Could be a problem with the scope???

Check all your screws first. If nothing is loose, try sitting your gun on a lead sled or sandbags. while aiming at a target, try adjusting your scope to see if the rosshairs move.

What's your bullet speed? If you haven't checked it, could be it's slower than you think. And yes, could be the scope. I've had more than one fail.

I doubt if it would adjust to 200 and be on with a screw problem. I am going turret issue. I would shoot a dot pattern to make sure it adjusts right. I.e. Adjust 1 mil and make sure the poi moves the right distance. Do it in all 4 directions.

Couple of things to think of real quickly, wind in the face will slow a bullet down, wouldn't expect it to do that much but maybe gusts are stronger than apparent?
Second, is there a possibility mirage is hurting your sight picture? It's hot out there and barrels heat quickly in this heat, so it's possible, but that would affect groups more you would think rather than just y axis.
Third, as mentioned above bullet speed is probably slower than you are getting ballistic data for. .308 tend to be shorter barreled guns, but this is just an assumption so that may not be anything.
Fourth, the ballistics calculator may be off. Did you double check with a different calculator?
Fifth, the range may be wrong on the distance. Did you double check that as well?

Just a couple quick things to check off.

Also the ctr has a 20 inch barrel and most manufactures use 24-26 so you will be slower than the box.

Ok, probably start with shorter barrel- how does one determine what drop the 18 or 20" would have? More math or shoot more to know the rifle?

Use a chrono to Get the velocity to know for sure... The other way is to measure the drop at a know distance i.e. 100 yard to 200 yards is xx inches and put that into your calculator. The rule of thumb is 25 fps per inch

Using gun data ballistics calc, adjusting 150ft/sec off for shorter barrel and giving a 15 mph headwind only have a drop at 300 of 9.4 inches, you are way over that (7ish with the .7mil adjust plus the 15-16 inches you shot low) at around 22-23 inches of drop. There has got to be something else going on than just the simple stuff....maybe.

Question: did you dial up instead of down, not paying attention to what you were doing? Although that wouldn't make sense since when you dialed more in (1.5mil) you were less low but still low.

What's your barrel length?
What scope are you using?

Typically the difference between 200 yards and 300 yards is in fact an additional .6 to 1.0 Mil.

You impacted low, saw the correction, and adjusted accordingly, and it was still low. I'm leaning toward the scope.

The CTR is a 20" barrel. I haven't shot through a Chrono so I don't know my actual speed.

For a little clarity when I said I was still low, when I adjusted scope it did adjust I was just still lower than I thought I should be.

The wind could have been stronger than I thought, it was hot and there was a lot of mirage.

I am using a SWFA SS 5x20x50

I am hoping to go shoot again on Saturday, but gotta find another place to shoot.

Excellent scope! So it was shooting consistently, but was lower than you thought it should be? There's an old saying "believe the bullet". If it's hitting consistently low, then lower your MV in your ballistic calculator until it matches.

I have this identical rifle with a Vortex Viper. I don't have a chronograph and am really interested in learning what velocity you are getting. I'd appreciate a PM once you find out.

You're probably running 2700ish with that bullet if it's a factory load.

You can also enter your corrections for various yardages and get your MV, (using Shooter). P_102

Something is screwey. This is the data for that bullet, with a 200 yard zero, at 2700fps, with a 10mph wind. Did you verify the target you were shooting at was definitely 300 yards away?

I'm pretty much a novice at long ranch shooting, using scopes with turrets etc.

You state you zeroed at 200 yards and then shot at 300 yards. Does your come up/dope correlate to a 200 yard zero or a 100 yard zero?

This may sound silly, but I've done it.....did you make your first adjustment the wrong direction?
The drop at 300 shows 7.6 inches but you shot 15-16 inches low, exactly where you would shoot if you
dialed the wrong way. P102

Since this is something you need to do anyway to make sure your scope is tracking correctly and your gun/scope combo is level do a Tall target test. There are video's out by Bryan Litz and others I am sure that show the procedure.
Main points 40-50 in tall target at EXACTLY 100 yards. Sight-in at 100 then put dot at bottom then dial up 5 MIl/10Mil/15Mil and see how the shots measure out and I drop a plum-bob to check they are going vertical.

Here is my new 308 from last week with 200gr Bergers. 3 Shots in middle were sight-in... this gun has a 30 MOA base vs my old one had 20MOA. This scope is MOA so I did 10/20 but 30 would have put me over the top so I quit there. The bullet holes measured out perfect so the scope is fine .. which I knew from the previous test but wanted to make sure it was level.
I have learned that most times when the numbers are off badly its because the rifle is NOT zeroed properly so make sure of that and I recommend doing that at 100 to eliminate error.

I'm showing a .7 to a .9 mil come up at 300 yards from a 200 yard zero, and no more than a 1 mil come up. If you are dead on at 200 and a .7-.9 come up does not get you on, something is strange. The main thing is having a dead nuts zero to adjust from. With the data you listed, something is not lining up correctly.

(.7 is about 2650 fps, and .99 mils is at 2450 fps, which is very slow for a 165 grain)

Any chance you were thinking your turret clicks are in .25 MIL adjustments instead of .1 MIL?

Scope is either .1 mil or Moa...


Where do you shoot? I may be able to meet and bring my lab radar out to get it figured out

MV, BC can be ignored right now. He saw a low miss, dialed the correction, and the next shot is still low. The scope isn't doing what it is told to do.

Agreed. But mv is easy to get to help guide further trouble shooting.


I would run a dot drill to see if the scope is responding right.

Another question is when it was sighted in did poi move accordingly? Or did you have to over/under adjust to get it on at 200