 Shooting my 338 LM @ 2200 meter 

03092012, 11:32 AM

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Join Date: Jan 2010
Location: utah
Posts: 366


Re: Shooting my 338 LM @ 2200 meter
Quote:
Originally Posted by Yrcan
That's strange, but maybe true.
But in the manual from Millett, it states that 1 MiL = 25x.
I took a shot @ 1350 meters 2 weeks ago@ 25x, and used the dot's for holding the windage, it was spot on from what Shooter came up with.
Maybe something is different with my new LRS1. ???

could be mine has dots and bars on 12.5 from dot to bar is 1 mil on 25 dot to dot is 1 mil and dot to bar is 1/2 mil

03092012, 11:39 AM

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Join Date: Jan 2010
Location: utah
Posts: 366


Re: Shooting my 338 LM @ 2200 meter
Quote:
Originally Posted by Shumba
Bruce makes a great point that has been overlooked. All of what he stated above could be the culprit. Need a emoticon that shows slaping the forehead as in, "Duh, why didnt I think of that!" lol

i doubt it with this scope. i have one and and have shot it out to 2000 yrds. one minute is one minute at least on mine

03092012, 11:42 AM

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Join Date: Jan 2010
Location: utah
Posts: 366


Re: Shooting my 338 LM @ 2200 meter
Quote:
Originally Posted by M67
Undoubtedly, the question is simply what variable is SO wrong?
I have done my share of lobbing 308 and 6.5mm to "impossible" range, almost always "sighting in" on the spot, as temperature measuerement is by nose and ass, and pressure by weater forecast, etc.. the 6.5 becomes effectively unspottable beyond 1500m as we do not have desert sand here.
However:
I have been pestering Yrcan over this and i am convinced that all the normal variables are accounted for and used well within accuracy that should yield less than 1/10 of the error we are seeing.
Running my ovn dope i get between 40.0 and 44.0 mil UP, considering the probable met/env at Yrcans site.
Changing variables
Temperature: 1°C is 0.015mil /
Pressure: 1hPa is 0.044mil
Direction: 90 vs 270° is 0.5mil
headwind: 1m/s is 0.06mil
velocity: 1m/s is 0.11mil
Humidity: miniscule effect, and anyways close to 100% in all Yrcans shooting
BC: 0.010 of G7 BC is 1.2mil (in comparison it is 0.3@1350m)
Range: 10m is abouts 0.44mil
As far as i can tell from experience with measuring all these variables, at distances beyond handheld lasers, range is by far the most challenging. I estimate Yrcans temp, press. and other measuerements to be accurate within 23units of measurement. Wind probably far better, as we can see there is very little wind anyway.
Range has been remeasured using different maps, GPS, etc.
For any probable error in variables other than BC, the range must be over 2300m, which it is not.
Thus, as i see it we are left with BC, obviously very important at this flight time (5.3s)
The question becomes then, does the G7 BC change with velocity, and does it change on the order of 0.02 units?
Does it change at the speed of sound? After all the bullet is travelling 600m, and for 2 seconds, below the speed of sound. If this is the case, the only solution will be a custom drag model, or to tweak it with different BCs for different ranges, or to use a bullet that fits the existing drag model.
Maybe the bullet enters a region of dynamic instability, and is coning , or some kind of limit cycle oscillatons  thus increasing drag?
K

your dope was 44 mils? x 3.5 moa=154 moa or close to what it took to reach the rock by his scope? sound like the original input may have been missing som things

03092012, 01:11 PM

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Join Date: Dec 2010
Location: Colorado Springs
Posts: 581


Re: Shooting my 338 LM @ 2200 meter
Thanks for sharing.
__________________

03092012, 01:38 PM

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Join Date: Oct 2010
Location: Norway
Posts: 69


Re: Shooting my 338 LM @ 2200 meter
Ok.
I have done some math. Not my strongest side, so correct me if I'm wrong.
I dialed 103.5 MOA for 2000 meters. This is 30.2 MIL
I have then calculated that 5.5 mils @ 14x in the Millett, equals 9.8 MIL
Ergo, I am at 40 MILS at 2200 meter.
My input regarding MV is 861 m/sek, M67's MV for 44MIL is 835 ish m/sek. Don't remember his exact MV.
4 MIL difference @ 2200 meter = 8.8 meter. We have a MV variation of 26 m/sek, so I do not think my inputs are as bad as they might seem in the first place
My goal with this shooting was not to find out how many MIL or MOA I needed to get there. I was hoping to prove that I could shoot a nice consistant group at the given distance. When I get my steel or cardboard target up, we will see just how well I can group my shots.
Regarding bullets and BC, I shot a 300 grs SMK using G1 BC, with a slight adjustment.

03092012, 05:26 PM

Silver Member


Join Date: Jan 2010
Location: utah
Posts: 366


Re: Shooting my 338 LM @ 2200 meter
Quote:
Originally Posted by Yrcan
Ok.
I have done some math. Not my strongest side, so correct me if I'm wrong.
I dialed 103.5 MOA for 2000 meters. This is 30.2 MIL
I have then calculated that 5.5 mils @ 14x in the Millett, equals 9.8 MIL
Ergo, I am at 40 MILS at 2200 meter.
My input regarding MV is 861 m/sek, M67's MV for 44MIL is 835 ish m/sek. Don't remember his exact MV.
4 MIL difference @ 2200 meter = 8.8 meter. We have a MV variation of 26 m/sek, so I do not think my inputs are as bad as they might seem in the first place
My goal with this shooting was not to find out how many MIL or MOA I needed to get there. I was hoping to prove that I could shoot a nice consistant group at the given distance. When I get my steel or cardboard target up, we will see just how well I can group my shots.
Regarding bullets and BC, I shot a 300 grs SMK using G1 BC, with a slight adjustment.

ok im confused a mil is a mil is a mil or 6280 mils in a circle. you mean dots at 14x=9.8 mil?
great shooting anyhow!! bottom line is to verify what anyrifle does at anyrange given to shoot. great job I look forward to the sequel

03102012, 09:15 AM

Bronze Member


Join Date: Oct 2010
Location: Norway
Posts: 69


Re: Shooting my 338 LM @ 2200 meter
Yes you are correct. Dots are 1.785 mils @ 14 x in the Millett. (1.785x5.5 mils= 9.8mils holdover @ 25x) Are you more confused now ;)
I am now saving up money to buy the IOR 1252x56 Terminator.
Should be a nice scope for my beloved rig.
100 MOA adjustment, and really good glass, combined with high magnification should be a nice tool for spotting deer and shooting targets at long range. I will ofcourse shoot deer with it aswell.
We have a bag limit of 50 deer where I hunt, so there should be some good chances of shooting one at a long distance.
Hope to have my target up and running by next saturday, and maybe I can post the results here then.



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