Shot FGMM 175gr. for DOPE out of a 20" 1/10" barrel, 20 MOA scope base, Seekins 1.45" AR rings, 2.60" above bore. NF NXS MOA. Laser ranged. Elevation 800', Temp. 60F. The results: 100/Zero, 200/4 clicks up, 300/20 clicks up, 400/24 clicks up. I cannot get JBM results to match DOPE. Any opinions?
DOPE not making sense
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Don't confuse your actual elevation with the Density Altitude. Your bullet flys in the density that is present, which can be different. Reading your post I'm not sure exactly what JBM predicts and what your actual was, so I don't know how large the difference is. Have you done a tall target test? What do you mean bu "clicks up", are you refering to 1/4 moa clicks on your elavation turret?
Well, first of all, stop calling them clicks and use the actual measurements on your dial. That way we can all understand what your numbers really are. Since you are using a NF NXS in MOA, each click is 1/4 (.25) MOA, so you are saying that at 200 (Yards I assume?) you had to dial only 1.0 MOA, at 300, 5.0 MOA and at 400 you were at 6.0 MOA. If everything else is correct, then you are right, it does not make sense. That trajectory does not compute, so somewhere you got something wrong.
For the standard FGMM in 175g running about 2650 fps MV, your numbers should look something like 2.0 MOA at 200 yards, 4.7 MOA at 300 yards and 7.9 MOA at 400 yards. Or in your terms, 8 clicks at 200, 19 clicks at 300, and 32 clicks at 400.
So, you need to either verify the yardages you zeroed and were shooting at or you need to check the turrets on your scope and make sure they are working properly. You will note that your 300 yard number is almost dead on.
For the standard FGMM in 175g running about 2650 fps MV, your numbers should look something like 2.0 MOA at 200 yards, 4.7 MOA at 300 yards and 7.9 MOA at 400 yards. Or in your terms, 8 clicks at 200, 19 clicks at 300, and 32 clicks at 400.
So, you need to either verify the yardages you zeroed and were shooting at or you need to check the turrets on your scope and make sure they are working properly. You will note that your 300 yard number is almost dead on.
Sure you weren't 34 clicks at 400 you would have to running pretty fast out of a 20" barrel to only be 24
That's only one reason why he needs to stops counting clicks and actually read what the actual number on the turret is.
Is this the kind of post you like to see when you start a thread asking how to put a bolt in your rifle, or wondering why the wrong mags will not fit?
I have a Remington 700 Mil Spec with the barrel cut to 20" and using Federal GMM in 175 grain my dope is very close to yours....200 yds = 1.5 moa / 300 yds = 4.5 moa / 400 yds = 7.0 moa / 500 yds = 10 moa / 600 yds = 15.0 moa. This is using MV of 2,660 fps with 1,250 DA and temp about 65 degrees, change any of these variables and the dope changes with it. This is why you need to keep a dope chart and not solely rely on ANY ballistic calculator.
I agree, was that a typo? If you're talking MOA with a 1/4 click adjust, I get 8.22 MOA (33 clicks). My data is almost identical to yours with same barrel and ammo. You must be inputting something wrong to the JBM calculator.
Or he's making the mistake of trying to count clicks instead of reading the dial to get his Moa reading.
You haven't got dope yet, you have the output from a ballistic calculator.
Dope is the verified data from previous engagements.
Once the bullet tells you how far it is actually dropping you can adjust the BC or the muzzle velocity in your calculator.
Density altitude will play a part in this as it effects the bullet's trajectory.
Dope is the verified data from previous engagements.
Once the bullet tells you how far it is actually dropping you can adjust the BC or the muzzle velocity in your calculator.
Density altitude will play a part in this as it effects the bullet's trajectory.
Thank you for the replies. I was comparing my range data to the JBM calculator to try to get an estimated velocity based upon the 200 rnds of FGMM 175 I sent down range. I zeroed at 100yds and fired several groups confirming POA/POI were the same. I moved back to 200yds and fired my first group and adjusted elevation and fired severa groups to confirm POA/POI with the 2 MOA ((4) 1/4 moa clicks or #1) on the elevation adjustment. Same process for 300yds with confirmation of 5MOA ((20) 1/4 moa clicks or #5 on the dial) of elevation necessary. So at 400yds for POA/POI it seemed odd that I only needed 4 additional MOA ((24 1/4moa clicks or #6 on the dial). I was expecting more drop from 300 to 400yds.
Ballistically speaking the bullet will drop more from 300-400 yards than it did from 200-300 yards so either:
1) there is something wrong with your optic
2) there is something wrong with how you are using the optic/recording data
If you are using an IOR, try changing optics.
1) there is something wrong with your optic
2) there is something wrong with how you are using the optic/recording data
If you are using an IOR, try changing optics.
It is good to have a ballistic calculator and a confirmed dope chart to compare it to. A physical dope chart is set for particular variables in a particular environment. The ballistic calculator is a great tool to be able to adjust to your variables for the current environment.
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