Over the weekend I had a chance to shoot on a friend's range that goes out to 1,200 yards. I've never shot past 400, but felt confident I could out shoot most everyone in the group as only one of them had shot past 200 on paper.
At 400 and 500, I simply used my B&C reticle and was able to make good hits on a 3" orange dot painted on a 4'x4' steel plate. So then we backed up to 800 yd and painted a volleyball sized dot. I dialed up 17.75 MOA as per my Strelock app and missed bad low on the first shot. Next 3 shots, I held about 18" over the dot and shot a respectable 12" group centered around the dot. Then we backed up to 1000 yards and I missed the entire steel plate twice and gave up as it was getting hot and we were hungry.

I know for some of you with long range equipment and experience this is easy, but with a stock hunting rifle I thought a 12" group at 800 was decent, considering the bench and rest situation wasn't great and I was sweating like crazy.

Here is my question. Why were my 800 and 1000 yard shots so low in comparison to what Strelock said? Does Strelock take into account the changing BC of a bullet as it slows down? Was it my scope adjustments that may or may not be exactly 1/4 MOA per click? Was it just me not applying all the factors correctly?

Here is my specs:
7mm08 with 150 gr LRAB at 2750 fps
BC = 0.59
Scope to Bore = 1.8"
Weather = 85*
Leupold VX3 - 3.5x10x50 with B&C, no turrents

Can one of you guys run the numbers with some better software for me? Thanks in advance.

With the info you gave, and if you are zero'd at 100 yards, JBM ballistics shows a 29.2 MOA (306") drop at 1000 yards.

There's a lot of variables that could be contributing. Number one by a wide margin would be the adjustments of the scope. Back when I did use Leupolds the values were all over the place. In order to get anywhere I'd map each one on paper at 100 yards, it wasn't uncommon to see click value off by 30% vs what the turret claimed, though others were pretty close. Number two would be the BC of the bullet, some of the LRAB's have been pretty wildly off, though I don't know about that individual one and my latest Litz book is packed away right now.

I show you at 20.7 MOA up at 800, if you held a true 18 inch hold-over, that would put you about the 2-3 MOA that you were short in your dialing.

I show 29.9 MOA and 312.7 inches at the 1000 yards mark, but it's rough math only - NV is seeing about the same.

I'm guessing a "fat-finger" data error combined, with some scope error.

I also noticed you didn't add any wind data - which plays a big factor as well.

Your BC should be about .576 for that bullet and velocity assuming your shooting a 9 twist. Many other factors come into play such as mirage, parallax and cant.

What is your zero range and how high is bullet impact at 100 yards?

This is what I'm thinking in hind sight because my 400 and 500 yard shots were very good using the B&C hash marks. Things went downhill when I started dialing. I didn't even think about that until the next day.

This was my first assumption in the field, but I posted on the Reloading forum here and Mule Deer responded quickly that the BC was actually very close on that bullet according to Litz.

I was zeroed at 200 and the wind was almost non-existent (which is why we were sweating so bad......August is not the best time to shoot in MS). When we did get a slight breeze, it was in our face.

AH64guy, it's interesting that your MOA calcs are almost exactly how much I was off at 800. What program is that?

I hope to get to go back to this range soon and try again. We all had a lot of fun as none of us had ever shot anywhere near that far.

9.5 twist Browning X bolt. Definitely was fighting some mirage. Zero at 200. About 1.5" high at 100.

I'd wager your scope is off.




Dave

Brian Litz just tested that bullets real world G1 BC at .576

Try plugging that BC number in your ballistics program and see how much of that 18" drop error it accounts for @ 800 yards .;)



http://www.longrangehunting.com/threads/nosler-lr-accubonds-bc-testing-results.137554/

To the OP, if it makes you feel better I am also only a novice LR shooter. I find I can make very consistent hits to about 850y even with only a 9x cheap scope and a .223 RAR.

When I go to 1000, my inexperience and mediocre gear is shown up in a hurry! Hits are much harder to come by.

Shooting at 1000+ is hard! A lot harder than some people on the internet make out, or than some of the more skilled shooters make it look.

Difference between .576 and .59 is about 1.5" at 800 per Strelock

Try using a different ballistics program.

Get a quality ballistic solver and make sure you've measured all inputs accurately. You'll get good output data.

[quote] AH64guy, it's interesting that your MOA calcs are almost exactly how much I was off at 800. What program is that? [quote]

Shooter Ballistic App by Shaun Kennedy shooterapp.com

It's in the Apple store, and I've used it for about three-four months now.

Thanks. I was actually pleased with my shots at 800 once I adjusted my hold-over. A 30x Nightforce would have made a big difference!!

This is what I'm thinking.

For long range first round hits you will need , as a minimum, exact velocity, exact BC's for your conditions and twist rate, exact distance to target and exact scope correction factor.......then there is wind, mirage, shot orientation.......then the platforms capability.

Lots to it , but the science can be figured out fairly easily with the proper tools.

I'd wager his ballistic app and inputs were off also. Although he should really verify the tracking of his scope if he wants to start shooting long range.

With my Leupold 3.5X10 on 10 power, at 300 yards, 2 clicks move my POI about 3" or a tad more, 3 clicks about 4 inches.

This is with a 27 inch barreled 30-06, using factory Hornady 150 gr. Superperformance SST ammo advertised 3080 fps.

Book value is 1 click = 1/4" at 100 yards, which I haven't tried...

So as said, you need to "regulate" what your settings actually do, at the ranges you shoot.

I have had 2 Leupold 3.5-10 scopes that the last revolution of the elevation turret did not move the cross hairs.
If you are going to dial do not trust a Leupold

Well, not without verifying it at several range sessions.

A 6x or 10x SWFA milquad scope may save you a lot of time and frustration.

Very good advice...

Leupold MOA scopes are NOT 1/4" clicks at 100 yards. They are true MOA, which is 1.047" at 100 yards, or .26" per click at 100. This of course compounds as you move to distance.

Second, I didn't see anywhere where anyone suggested looking at atmospherics. They play a drastic role in your dope, especially when you get past 700-800 yards. If you're doping for one density altitude, but shooting in another you can easily miss targets at 800-1000 yards. It's important to make sure you have barometric STATION pressure, along with actual altitude and temperature. Set humidity to 50% and forget about it. If these settings aren't taken in account for those distances you can easily miss your target.

Actually if you are going with station preasure, you can ignore altitude all together. Altitude is only needed if you're using barometric pressure. If using baro, altitude is used to calculate what air pressure should be above sea level at your location which may not accuratly reflect your atmospheric condition. Station pressure is most accurate since it reports actual environmental preasure in the area the intended shot will occure. Knowing the actual preaaure, temp, and to a lesser degree humidity is far more important since this physicaly influences the projectile flight path between shooter and target no matter the altitude.

Altitude is important only if using barometric pressure. Without altitude you cant calculate preasure above sea level. Air has less density the higher the altitude becomes. Other factors that influence air density of course is temp and humidity to a lesser degree. It is the density of the air which affects drag the ballistics resolvers are looking for.

Other things that affect bullet flight over ELR shots are wind speed, wind direction, spin drift, and the coriolis effect. Then you need to input twist rate of your tube, and azimuth for coriolis, and a kestrel for wind speed. Get a kestrel with applied ballistics, and practice.

The only way station pressure doesn't need any adjustment is if the "station" is at the exact altitude you're shooting at and in the local vicinity. Since National Weather Service (NWS) reporting stations across the country are located at numerous altitudes, their reports are normalized to sea level to allow the NWS to make maps of pressure changes over distance. The normalized sea level pressure is also useful for anyone nearby by making a simple adjustment using the altitude at your current location.