300 wsm Ballistics help

[razorrt5]

Hey all, Hoping someone would have a good answer for me about some mid-range ballistics.

Situation: I'm shooting a Savage 110 Ultralite 300wsm (1:10 twist) with a Omega300 sup. and pairing that with Federal Terminal accent 200gr. I've chrono'd my rifle and averaging 2804 ft./sec. (ammo box states 2810) using both the Hornady ballistics app and the vortex LR calculator to get a dope but the calculation results are not correct. see below for calc

Hornady Ballistics calculator (Vortex calcs within .1 MOA)
100yd - 0 MOA
200yd - 1.31 MOA
300yd - 3.51 MOA
400yd - 6.09 MOA

But data from actual shooting at the range is telling me the following:
100yd - 0 MOA
200yd - .8 MOA
300yd - 1.65 MOA
400yd - 3 MOA

am I missing some big factor on the ballistic apps? I'm consistently hitting a 4" plate with a 3MOA adjustment when the calculators tell me 6+ MOA... I'd like to trust the app so that I can make adjustments in the field out to that 500-600 yard range. Thanks for your helpful knowledge in advance! - Ryan

 

[Addicting]

I've chrono'd my rifle and averaging 2804 ft./sec.

How far was the chrono from your muzzle?

Is your scope height set right in the app?

Did you use the right Drag Function in the app?

When I see these discrepancies it usually means bad data was inputted somewhere. Bad in equals bad outputs.

 

[razorrt5]

How far was the chrono from your muzzle?

Is your scope height set right in the app?

Did you use the right Drag Function in the app?

When I see these discrepancies it usually means bad data was inputted somewhere. Bad in equals bad outputs.

Thanks for the response.

1. I was about 6-8' from the Chrono as suggested in the manual due to muzzle blast.
2. Scope height is 2.25"
3. Drag, using G1 at .608

I did double check and they are all set correctly. I fiddled around with the variables just for kicks and I would need to be at 3500ft/sec. to get near the same dope but that's clearly not the case

 

[utah400elk]

How did you determine your BC? I have found a lot of manufacturers inflate their BCs. Something to think about…

 

[Forkyfinder]

Id use a g7 bc, but you are getting discrepencies that dont quite add up. You wouldnt get close to that trajectory at 10000' elevation.

You might try a box test at 100 to confirm your scope is adjusting correctly.

 

[Wind Gypsy]

The BC isn't going to make a ton of difference at 400 yards. I'd bet your zero is not perfect (a little high) and your actual velocity is a little higher and possibly your scope doesn't track correctly.

What kind of scope do you have?

How many shots and how big are your zero groups?

Also, 2.25" sight height seems off. I have high UM rings on my hunting rifle which gets the scope up higher than most hunting rifles out there and I'm below 1.8" height above bore. That isn't causing 2 MOA of error but you might as well get that right.

Down drafts, shooting a a steep angle and not compensating for that are other possible causes of error.

Probably shouldn't be shooting out to that 500-600 range at game.

 

[Addicting]

Also, 2.25" sight height seems off. I have high UM rings on my hunting rifle which gets the scope up higher than most hunting rifles out there and I'm below 1.8" height above bore. That isn't causing 2 MOA of error but you might as well get that right.

Nailed it.

This is way off, 2.25” to the center of the scope is some extremely high rings. Are they see thru rings?

 

[ropeup79]

Also need to have the elevation correct. Most calculators have sea level as the standard. Temperature and humidity can have an impact also.

 

[razorrt5]

The BC isn't going to make a ton of difference at 400 yards. I'd bet your zero is not perfect (a little high) and your actual velocity is a little higher and possibly your scope doesn't track correctly.

What kind of scope do you have?

How many shots and how big are your zero groups?

Also, 2.25" sight height seems off. I have high UM rings on my hunting rifle which gets the scope up higher than most hunting rifles out there and I'm below 1.8" height above bore. That isn't causing 2 MOA of error but you might as well get that right.

Down drafts, shooting a a steep angle and not compensating for that are other possible causes of error.

Probably shouldn't be shooting out to that 500-600 range at game.

I'm using a Vortex Viper 6.5-20x50 BDC. I double-checked the scope height and it is correct at 2.25" from the middle of the barrel to the middle of the scope. I'm shooting 3 shot groups and my zeros are within a half dollar on or touching the bullseye. I've adjusted for elevation, temp in the calculators as well recalculated with G7 and the results are no different. I feel like I'm taking crazy pills lol

 

[Fire_9]

I would make sure you have a good zero. There is no way you're dialing a true 1.65 moa for 300. Something is wrong with your zero, scope, or rifle

 

[Fire_9]

Almost every rifle is going to be right around 3 moa for 300 yards give or take maybe .5 moa. I can guarantee you that 1.65 is not correct

 

[Wind Gypsy]

I'm using a Vortex Viper 6.5-20x50 BDC.

There’s a fair chance it doesn't adjust correctly.

I double-checked the scope height and it is correct at 2.25" from the middle of the barrel to the middle of the scope.

what rings/bases do you have? That is very high.

I'm shooting 3 shot groups and my zeros are within a half dollar on or touching the bullseye.

Are you saying your 3 shot groups are within the size of a half dollar and that dispersion is centered or touching the bullseye? If you are just within a half dollar of the center of POA, that allows over 1 MOA of error in your zero. Also, 3 shot MOA+ size groups could easily be inflicting half MOA of zero error or more.

I've adjusted for elevation, temp in the calculators as well recalculated with G7 and the results are no different. I feel like I'm taking crazy pills lol

I'll stick my my initial guess of most likely factors - Zero error, lower velocity than actual, scope function. Could all be working in concert with each other to add up to that much error.

The calculator outputs are not wrong, something with your shooting or equipment is off.

 

[razorrt5]

double checking all the things as all commented on, I then talked to Vortex and they asked that I try a test at the range with the paper and BDC crosshair measurements.... given all other things are correct and my accuracy is consistent it might be bad glass etching

 

[matthausarchery]

I would recommend shooting a large target at 400 without dialing. Shoot a group of 5 shots letting your barrel cool. Measure from point of impact to point of aim. Let ua know what you find out.

 

[jimh406]

I would change the parameters in the calculator and put 1.5 for the scope height which is fairly standard and see how you compare.

It's just math and doesn't require shooting. As others have noted, 2.25 is very high it will impact your dialing.

 

[millerkiller77]

Almost every rifle is going to be right around 3 moa for 300 yards give or take maybe .5 moa. I can guarantee you that 1.65 is not correct

This spot on. I'm dialing 3 at 300 with multiple 300wsm

 

[rjthehunter]

Something is wrong with the scope. Unless you're zero is at 200 yards, then maybe.

With my 338 at 300 yards, it calls for 3.4 moa.

 

[Wind Gypsy]

If you are dialing the corrections, I don’t see how the reticle etchings would have any impact on it.

 

[rjthehunter]

If you are dialing the corrections, I don’t see how the reticle etchings would have any impact on it.

Maybe he's holding over? That'd be the only way

 

[turbobrick]

Maybe he's holding over? That'd be the only way

I was wondering if he was holding over too. That reticle is only going to be correct on the highest magnification. So if he is not all the way on 20x, that could very well be where this error is coming from.