Hello, I recently shot at the 300 yard range with a 6mm BR. I was using Hornady 105 BTHP-M and 2500 fps to initially dial in. I dialed 5.4 MOA. The velocity average was 2570 via Labradar and the group was about 1.5" higher than I dialed (2570 dial would be 5.1). The scope is a Nightforce NX8 F2. I tried 2 other powders and loads (2480 and 2760 avg velocities, same bullet) and only one load had the dial-in correct. All the others were high (one was 2.5" high). I doubt it's the scope as it's 2 months old. Any other reason the ballistic calculator and real world results are so off? My dope card should be the real world results, correct? If so, how much lower should the dial-in be, (dialed 5.4 MOA that was 1.5" high---if I dialed 5.1 instead of 5.4, would the 0.3 MOA difference lower the group 1.5"? Thanks.
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Question about estimated vs. actual scope MOA calculation
- Thread starter YamaS3rider
- Start date
data in data out. a ballistic calculator isn't that far off...especially at 300y
check your zero first for sure
confirm both your 100y zero and 300y target distances are correct
any offset or other error mistakenly entered in the BC
i get 5.1moa from a quick use of the hornady BC
dialing an extra .3 definitely makes a difference of around 1 inch give or take, then account for any wind or error in rifle zero and 1.5" is not that far off
check your zero first for sure
confirm both your 100y zero and 300y target distances are correct
any offset or other error mistakenly entered in the BC
i get 5.1moa from a quick use of the hornady BC
dialing an extra .3 definitely makes a difference of around 1 inch give or take, then account for any wind or error in rifle zero and 1.5" is not that far off
With regard to this, do I measure from the center of the barrel to the center of scope body or scope objective?
Center barrel to center body tube. Closest to the turret seems to be what most people agree matters
Agreed.
When the HOB gets tall, like on a semi auto, the 100yd zero gets dicey as its not clear if the POA and the POI are still closing together or opening up yet. Try zeroing at 200y and then just dial down your 2.2moa, call it a 100y zero, and set your zero stop (or whatever) there no matter where it is. You won't have to worry about a precise HOB measurement or a ballistic calculator that properly handles HOB and it'll be close enough to hit at 100y and won't give you that HOB starting uncertainty so all the other ranges will follow the ballistics calc.
This side of the sport gets stranger and stranger.
Also just a quick reference, if you assume 1 moa as 1"per 100yds (so shooter moa or smoa)
1 moa @ 300y = 3"
so your .3moa dial up error = .9" (call it an inch)
1 moa @ 300y = 3"
so your .3moa dial up error = .9" (call it an inch)
Ok....a couple of things.
First and foremost, STOP trying to say that you missed your point of aim by x inches. Use the reticle to measure the miss. You can then adjust your DOPE and dial.
So, you shoot and miss the point of aim by some ANGULAR measurement and using the reticle, you see that you are so many little scope marks too high (for example). You then dial down whatever that many little scope marks is.
If you dialed 5.4 MOA and hit 1.5 MOA high, dial back down 1.5 MOA. Your real world DOPE for the conditions you are shooting in is 3.9 MOA for those conditions.
Note that you need to know whether your scope is first focal plane or second and if second, what zoom level it reads true.
Be sure to write that shit down and include temperature and density altitude and any wind. Try to keep a log of every shot you make at a range. I try but fail to log every range round fired. I do not try to keep a log while I am hunting.
Second, the ballistic calculator is fairly accurate but should only really be used to get you close. Actual impact data is what matters.
Third, as long as you have a scope that can be easily dialed (as opposed to one you adjust with a coin or screwdriver), zero at 100, shoot for verification and DOPE. If your scope is of the latter, choose an acceptable (to you) point blank zero, shoot for verification and DOPE it.
EDIT to add: It's a whole lot of reading with LOTS of fun and some real serious arguing and some real stupidity but there is some real good info to be gleaned.... https://www.snipershide.com/shooting/threads/moa-vs-mil.7060652/
First and foremost, STOP trying to say that you missed your point of aim by x inches. Use the reticle to measure the miss. You can then adjust your DOPE and dial.
So, you shoot and miss the point of aim by some ANGULAR measurement and using the reticle, you see that you are so many little scope marks too high (for example). You then dial down whatever that many little scope marks is.
If you dialed 5.4 MOA and hit 1.5 MOA high, dial back down 1.5 MOA. Your real world DOPE for the conditions you are shooting in is 3.9 MOA for those conditions.
Note that you need to know whether your scope is first focal plane or second and if second, what zoom level it reads true.
Be sure to write that shit down and include temperature and density altitude and any wind. Try to keep a log of every shot you make at a range. I try but fail to log every range round fired. I do not try to keep a log while I am hunting.
Second, the ballistic calculator is fairly accurate but should only really be used to get you close. Actual impact data is what matters.
Third, as long as you have a scope that can be easily dialed (as opposed to one you adjust with a coin or screwdriver), zero at 100, shoot for verification and DOPE. If your scope is of the latter, choose an acceptable (to you) point blank zero, shoot for verification and DOPE it.
EDIT to add: It's a whole lot of reading with LOTS of fun and some real serious arguing and some real stupidity but there is some real good info to be gleaned.... https://www.snipershide.com/shooting/threads/moa-vs-mil.7060652/
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Wrong, completely false and bad advice. Your ballistic calc should put you exactly on target if you gave it good inputs. To miss at 300 By over an moa means you have something bad going in that will only be worse if you shoot at real distance.
I dont think he is referring to ballistic calc numbers, I believe he is referring to dialing a correction on the scope is not changing the POI
the same as the correction.
the same as the correction.
OP is within 1/2 moa at 300y...
But I do agree that a ballistic calc should get you very very very close provided you give it good inputs
The guy telling him to ignore the calc thinks he’s 1.5 off and that would be okay. It is not.
There is some real serious lack of reading comprehension going on.
Ahem.
He’s not 1.5 moa high at 300. He is 1.5” high at 300.
Edit: OP, to repeat the good advice, make sure you have the scope over bore right, it doesn’t have to be .001 accurate but .1 should be easy enough to find. Middle of scope body to middle of barrel will do fine.
Next, make sure you zero with each of your various ammos (or at least record off set from zero) before proceeding to making assumptions at distance because different bullet lines will land in different places. You can’t blindly assume that all bullets will print at the identical place at 100 and then rush off to distance, you need to establish your baseline with a 100 yard zero.
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You know why no range was given?
Because the range doesn't matter at all. Not one single bit. If you look through the scope and use the reticle to measure and then use that info to adjust, it works at whatever range you are attempting.
Again, if your scope is SFP, be sure you know where it reads true or else know how to dial if you are not at that zoom.
Because the range doesn't matter at all. Not one single bit. If you look through the scope and use the reticle to measure and then use that info to adjust, it works at whatever range you are attempting.
Again, if your scope is SFP, be sure you know where it reads true or else know how to dial if you are not at that zoom.
Alternatively, SHOOT AT 200 YARDS to confirm what is going on.
100yd
200yd
300yd
This should all be logical in the same structure.
100yd
200yd
300yd
This should all be logical in the same structure.
First of all has anyone confirmed that the base and rings are properly torqued?
Has a tall target test and a box test been performed ?
It doesn't matter if it's a $200 or $2,000 scope. If it isn't installed correctly anything can happen.
It could have also had internal damage happen in shipping.
Secondly has anyone confirmed that the distance is actually 300Y?
I am a member at 3 ranges.
The first one is accurate to less than a yard.
The second one says 100Y yet it is actually 100M so nearly 10% off.
The third one is all over the place.
100y is actually 102Y, 200Y is correct, 300Y is actually 328Y, and 400Y is correct.
The 400Y gong is at 425Y.
As for club #3 there is usually nobody there and it costs $20.00 a year.
Secondly OP is using 3 different powders with a spread of 280fps between the 3 of them and the OP can't figure out why he is hitting high or low?
No mention on how accurate the loads were.
This is what I do when I have a new load that I like.
Zero the rifle at a known distance and input the chronograph velocity as well as all other pertinent data.
Get the ballistic data for the longest range available to shoot. for example 500Y.
If my ballistic calculator gives me 10.5 MOA I will dial 10.5 MOA and shoot a group.
If it shoots .8 MOA high I will shoot another group. If it is still 0.8 MOA high I will use the truing feature in the ballistic calculator to input the correction.
I will then shoot the 400Y with the trued calculations to see if it is accurate.
I will then shoot the 300Y in the same manner then the 200y.
Don't try to figure out 3 different powders at the same time.
Has a tall target test and a box test been performed ?
It doesn't matter if it's a $200 or $2,000 scope. If it isn't installed correctly anything can happen.
It could have also had internal damage happen in shipping.
Secondly has anyone confirmed that the distance is actually 300Y?
I am a member at 3 ranges.
The first one is accurate to less than a yard.
The second one says 100Y yet it is actually 100M so nearly 10% off.
The third one is all over the place.
100y is actually 102Y, 200Y is correct, 300Y is actually 328Y, and 400Y is correct.
The 400Y gong is at 425Y.
As for club #3 there is usually nobody there and it costs $20.00 a year.
Secondly OP is using 3 different powders with a spread of 280fps between the 3 of them and the OP can't figure out why he is hitting high or low?
No mention on how accurate the loads were.
This is what I do when I have a new load that I like.
Zero the rifle at a known distance and input the chronograph velocity as well as all other pertinent data.
Get the ballistic data for the longest range available to shoot. for example 500Y.
If my ballistic calculator gives me 10.5 MOA I will dial 10.5 MOA and shoot a group.
If it shoots .8 MOA high I will shoot another group. If it is still 0.8 MOA high I will use the truing feature in the ballistic calculator to input the correction.
I will then shoot the 400Y with the trued calculations to see if it is accurate.
I will then shoot the 300Y in the same manner then the 200y.
Don't try to figure out 3 different powders at the same time.
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Thanks, a lot of good suggestions. The culprit appears to be height over bore. I used the default of 1.5" but the actual is 2.1" which changes the dial from 5.1 to 4.7. As to some members asking....the rifle is zeroed at 100. The scope rings and base were torqued to specs. The scope was leveled using a scope leveling kit. FWIW, I'm new to longer distance shooting. I will check data at the 400 and 550 next...there is a qualification to shoot the 600-1000 yard range but I'm not ready yet...I've conceded that my rifles are more accurate than I am capable of shooting them. I've shot my Tikka T1x .22LR many times putting 10 shots into 0.5" at 100 so I have basic skill, but with my centerfire rifles, what shoots 0.5-0.6" at 100 is 2.5-3.0 at 300 and likely 6-8" at 550 for me (my eyes and impatience doesn't help). Anyway, I'm a gentleman of leisure now so twice a week at the range should encourage improvement.
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Ok, that’s all well and good. But let’s go back to those different powders. Did you try to dial each one in or just sling bullets for comparison? Which one did you settle on? HOW did you settle on it?
Then use that leisure time to learn how angular measurements work to manage trajectory including the conversion between angular measurements and the linear distance they subtend at any range.
It's kind of a basic rifleman skill
Ok, here was my thought process. I did a number of OCW tests and took the best results and then compared them at the 300 yard range. I changed the dial on each of the powders (Accurate 2015 had the lowest velocity at low 2500, BLC-2 was around 2600 and Varget mid-2700). All of the tests resulted in POIs that were high but then the velocities were higher than the previous velocity averages, so in the end I over-estimated drop. Going forward, I will test one load at a time, setting up a target at 300, 400 and 550.
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