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Trajectory mysteries.

All of this is useful, but the real mystery is that the calculations are accurate at 600, while being off at 300. Logically, any error should be exaggerated at the greater range.
Well, if no updates are available you might have just found a reason for one.
 
I don't trust or use ballistic programs, unless I'm generating dope for an oddball caliber I'm not used to. All I will ever use the ballistics program for is to get me in the ballpark, and I'm not worried if it's on or not; it's just to get me in the area. Once I'm in the area, I fine tune my dope and record for the present conditions.

I SWAG a lot. When I first had students showing up with 6.5 Creedmoor, I hadn't done a drop chart for it yet. I used the chart for a 175grn .308 and mentally adjusted the drop after we got past the first couple hundred yards. I do the same thing for temperature or elevation. The caveat here is that making corrections like this mentally are something I've been doing for years.
 
Using the Nikon, their ballistics calculator says that my load should be very close to being on with the scope set at 11 power, but I have to turn it down to 8 to be on at 300, which makes it very high at 600.
This works though right? Have you tried it at 400 or 500? It seems like you would need one more point of the curve.
 
I don't trust or use ballistic programs, unless I'm generating dope for an oddball caliber I'm not used to. All I will ever use the ballistics program for is to get me in the ballpark, and I'm not worried if it's on or not; it's just to get me in the area. Once I'm in the area, I fine tune my dope and record for the present conditions.

I SWAG a lot. When I first had students showing up with 6.5 Creedmoor, I hadn't done a drop chart for it yet. I used the chart for a 175grn .308 and mentally adjusted the drop after we got past the first couple hundred yards. I do the same thing for temperature or elevation. The caveat here is that making corrections like this mentally are something I've been doing for years.
Yeah, that's still above my pay grade. I need to get a lot more time behind the rifle at seriously long ranges before trying that.
 
I'm assuming you measured height over bore correctly?

I don't use them much but ballistics calculators are always wrong in my experience. They can get me on paper, but I never trust them.
Ballistics always has to be compared to the obvious (Art). Data is historical or inferred. Exterior ballistics in a trajectory is pure that is what we find in firing tables or reloading handbooks (Science). All other factors such as weather, location and actual MV must be added to find the total deviation from the norm (Science). Why trust something that tells you something that goes against your common sense (Art).
 
Ballistics always has to be compared to the obvious (Art). Data is historical or inferred. Exterior ballistics in a trajectory is pure that is what we find in firing tables or reloading handbooks (Science). All other factors such as weather, location and actual MV must be added to find the total deviation from the norm (Science). Why trust something that tells you something that goes against your common sense (Art).
This isn't just a ballistics chart. This is a well respected program that was created by one of the most respected ballisticians around. All of the factors you mention are taken into account and others are, also. It has been very accurate for me with other rounds in other rifles. And again, why would the calculations match perfectly for a 600 yard shot, but not a 300 yard shot? That's the real mystery.

This is concerning the M1a. The problem with the 300 WSM and BDC reticle doesn't worry me nearly as much as a failure of either the AB program or a Nightforce scope.
 
This isn't just a ballistics chart. This is a well respected program that was created by one of the most respected ballisticians around. All of the factors you mention are taken into account and others are, also. It has been very accurate for me with other rounds in other rifles. And again, why would the calculations match perfectly for a 600 yard shot, but not a 300 yard shot? That's the real mystery.

This is concerning the M1a. The problem with the 300 WSM and BDC reticle doesn't worry me nearly as much as a failure of either the AB program or a Nightforce scope.
Truth. Firing tables don't lie. Computations do when designed for the consumers or civilian market and not tested for all situations, bring it up to developer. There is no mystery it does or it does not. If it does not then it is broken.
 
I'm far from an expert in this arena but the redneck in me tells me that zero at 200 and 600 is good, so if 300 is 2 Moa low at 300, I simply aim a RCH higher at that range. That's what I would do if I were hunting, anyway...And I have taken them at 300 yards by simply knowing the approximate zero at that range, while aiming a bit high, and using a $150 scope with a single crosshair. But what do I know? :)

Bottom line, I would not place as much trust in the program as I would the results. If you are happy with the results at 200 and 600, leave it alone and compensate at 300 with your skill. Sounds like you have no other option.
 
Does your reticle have MOA marks for holding over? Confirm zero at 200. Hold, not dial for 300, see if it's the same thing. Need to make sure the scope is tracking right. Doing a box test would be even better. Also, what BC are you using? G1 or G7?
 
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