What the ____ am I doing wrong???

[shortpants]

I've spent most of the last year dialing in my MCR 300win, testing the Nightforce scopes click values and ensuring it to be level, and getting my hand loads as consistent as I could. I'm very pleased with the results I've had with the exception of one ongoing issue. I've got my ballistic program to match my actual drops within a click at all ranges out to around 1400yds. Things just don't match up after 1400yds.

I'm using the G7 drag model.

I have not even got close to the transonic range yet which would be close to 2000yds for this setup.

I would love to just blame myself or my hand loads for some kind of inconsistency and in no way am I implying that I could not improve in both areas. If it is something I'm doing or not doing I just can't figure out what it would be or how any type of inconsistency on my part could be to blame. I know that sounds a bit arrogant but let me give you an example of what is happening and you'll understand what I mean.

This is just one example but this same scenario has played out on several occasions.

This last Friday I setup to take my first cold bore shot of the day at 1330yds. like I would any other shot.
Plug in baro.,temp,latitude & heading, wind, range after confirming 3 times with PLRF05.
Spin Drift and Corriollis accounted for.
Ammo always kept in the shade (it's 80* here in the desert)
Parallax set
Bubble is level
Load the bipod
Using a rear bag shooting prone.
Good squeeze and BOOM!

Elevation was spot on but the wind call was off as this shot was across a very steep and unfamiliar canyon. I'm fine with that, hell that's why we practice so much right. I held more wind and sent another which was just off left a bit but again elevation was good. The 3rd shot hit its mark. I'm happy with this and this is typical of almost all the shots I take inside 1300yds.

After practicing shots at closer distances and even some shots off shooting sticks at 580yds (all of which were spot on as far as elevation is concerned) I ended my day with a rock at 1548yds.

I went through everything as listed above on the shot at 1330yds.
Good squeeze and BOOM!
The bullet impacted 3MOA low!!!
I adjusted and put 2 shots on the rock both at 7o'clock.

So how can the calculator and the actual hit differ by 3.25MOA when it was spot on at 1330? Like I said this is just one example but this same thing happened on a shot at 1407 and also at 1848.

If it is caused by some inconsistency in my form or my hand loads then why can I adjust after the 1st shot and make multiple hits in a sub-moa
cluster?

I've run these shot scenarios through Bulletflight which is what I've been using and also through Applied Ballistics which I just downloaded to my phone last night. I plan on using the ballistic calibration feature on AB next time I shoot. Maybe this might shed some light on the issue but even with a custom drag I have a hard time believing it can be so far off from 1300 to 1500.

What do you guys think???

 

[J E Custom]

1400 yards is a long way for a 300 win mag and the problem may be a simple stability problem
with the bullet.

You may have to try a different bullet style and weight with your twist rate to see if the problem goes away.

Just an idea.

J E CUSTOM

 

[yobuck]

Your looking for 1 ton performance from a 1/2 ton truck. Call MCR and order a bigger truck. lol

 

[bigngreen]

What bullet and velocity?

 

[406precision]

I assume you ran your tall target test out to at least as far as your shooting?

Sounds funny, but I have seen more than one scope start to stack after a revolution or two.

Jordan@406

 

[Jim See]

simple fix, like was mentioned the near end of turret travel may have something to do with it. Stop dialing past 1300 yards, use your reticule holdovers for the difference from 1300 to 1580 or whatever your shooting. Solution to your problem, at least you will know if that is the issue.

Typically BC can degrade with velocity degradation. I see this in shooting matches with my 6.5s after about 1100 I add a tenth of a mil for each additional 100 yards.

 

[toddc]

What load in a Winmag stays super out to 2k? At what elevation? 400000 ft lol.

 

[toddc]

Does sound like the scope is bouncing.

 

[bigngreen]

What load in a Winmag stays super out to 2k? At what elevation? 400000 ft lol.

I don't go transonic till almost 2100 yards with a 215 berger in my 300 Win 26 in barrel@ 2950, my 308 does not transition till over 1500 yards.

 

[toddc]

Good lord it must be nice to shoot at those elevations. At 5500 ft I am getting 1135fps at 1700 yds. I realize my program could be a hair off but thats a ton. Are you higher than 5500?

 

[shortpants]

Guys I appreciate the responses.
I built this gun specifically to be the ultimate 1 rifle for North America out to 1200yds. but know it is plenty capable of hitting rocks out past a mile. I don't want to turn this into a debate over calibers because I"ve already built the rifle so my mind is pretty much made up on that.
To clarify my bullet goes subsonic at 1915yds under the conditions experienced during the 1548yd shot. Altitude was around 3000ft.

I'm shooting the 215g Berger Hybrid out of a 28'' barrel at 2965fps.
G7 B.C. =.356
At 1548yds The bullet was traveling around 1418fps.
This rifle is sub 1/2 moa so shooting a rock at 1548yds thats about 3moa tall is not asking to much. The farther you can obtain drop data while still maintaining even 1moa groups is very valuable info for building a true algorithm to match your specific rifle/ammo.

I believe I have discovered the root of my problem. I tweaked my B.C. in order to make my calculator match exactly with my spotters calculator. This can work in one set of conditions but cause issues under different conditions. I believe this is at least part of my problem. I'm going to go back out and shoot again with my real B.C. this time and see what happens. Sometimes I just need to vent my issues out to the masses before the lightbulb goes off.

I'll keep you guys posted with my results.

Thanks for listening!
Jason

 

[jskmtd]

I don't think it is your bc degrading because I shoot the same bullet at near identical velocity and I don't have that problem shooting from 500 yards to past 1500 yards. Last Friday I took a cold bore at 1220 and watched the 215 land within a couple of inches of poa ranged another rock at 1527, dialed the scope, let it fly and watched the 215 land good for elevation but 3/4 moa right because of a bad wind call. I would agree with a couple of the previous posts that it is something with the scope.
Let us know what you find out.
Jon

 

[Canadian Bushman]

Slight deviations in barrel twist can cause different actual b.c.'s that will start to show up once you get way out there.

Check your twist and run the solution on bergers stability calculator for an estimated real world bc. If this number looks like what made your numbers jive id say you found your problem.

Id also try the same shot dialed and held over to comfirm its not the optic. If you have a gun vise you can test it on a scale without firing a bullet.

 

[J E Custom]

Going transonic is very important for long shots on non game targets, but at what speed does the bullet energy drop below the recommended level for the size of the game and the limits of the bullet
performance.

I 100% agree that any Good data can always help for more accurate shot placement but the type of target dictates the distance as far as I am concerned.

There are so many variables at Long distance and the father out you go , the more things start to degrade and sometimes you have to except the limits of your rifle and components.

Just my opinion

J E CUSTOM