Flatter than calculated trajectory

[Eagle Six]

I'm looking forward to whatever you figure out. A combination is most likely what has attributed to the difference. I think an updraft would have to be pretty strong, but you are there and I'm not. But anything not accounted for in the calculators being used can alter the results. Things like the tracking error of .25 MOA at a hundred just keeps getting worse the further we go out.

 

[17Hornet]

I'm looking forward to whatever you figure out. A combination is most likely what has attributed to the difference. I think an updraft would have to be pretty strong, but you are there and I'm not. But anything not accounted for in the calculators being used can alter the results. Things like the tracking error of .25 MOA at a hundred just keeps getting worse the further we go out.

Apologies for the late update.

We got out to the field on Sunday to do a bit more testing. Shots were fired at 500, 600 and 800 (angle compensated). My friend had brought the zero down 1/4 MOA between this session and last time I wrote.

Based on what we were seeing at that range, I used a G7 BC of .255 given ambient conditions. With that BC and a muzzle velocity of 3340fps, we are within margin of error at each distance (+/-.5" to group centre).

Now that we have a chart that appears to match closely to what we are seeing, we will be making another outing in a couple of weeks to confirm.

Also I had a mistake in my initial post. I had said that my friend's dialup was 6.25 at 600, when it was actually 6.5 MOA.

If the chart is validated, then this is what we were seeing:

-zero was off, accounting for 1/4-3/8 MOA
-we were achieving a G7 BC of .255 instead of .235
-there was an updraft in the valley, accounting for ~1.25 MOA

Thank you to everyone who took the time to help me with this!

 

[FeMan]

Glad you figured it out!

The updraft can be amazing. I was shooting at a mile last week in some 15 to 20 mph quaertering tail winds. I was two full moa's high due to the upslope effect of the winds. I was wondering what the heck my issue was until I went to pick up the target and felt the wind coming up the steep slope.