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School Me on Long Range Shooting 6mmBR

Texas10

The more I learn, the more I realize how little I know.....

Shooting my 6mmBR out to 1000 yds using 105 A-Max launched at 2866 fps out of an 8 twist barrel. Bullet is a hammer at 750 yds hitting a 6 inch steel with ease, however at 1000 yds it's all over the place. I'm talking several feet off target, or hitting the next target over. It should be doing 1447 fps at that distance, and Mach is 1150 fps at the 90F temp. Stability index is 1.66 at launch so I should be good there. Wind was mostly tailing at about 9 mph, and had little effect at closer distances except to dial back on elevation a few clicks.

Any ideas as to what's going on or why it goes unstable, if it is going unstable?

This has happened both outings where I tried to hit the 1000 yd target.
 
Welcome to wind. :) It's not linear so your wind hold at 1000+ can be close to double your wind hold at 700.

Tail winds are tough... they can switch slightly left/right on you and the angle change makes a big difference at distance. It's easier to shoot in a straight side wind.

Make sure your gun is dead nuts level - specifically the scope reticle. Any left/right cant in the scope will result in a big change in point of impact at 1000 yards. 1 degree tilt left or right is about 6 inches on target left or right.

Couple strategies for wind. BR or F class guys will have a spotting scope to read mirage to know what the wind is doing as well as watching wind flags. Tactical shooting has no spotting scopes or wind flags, so you just look at the overall conditions and also chase your impact using it as feedback in conjunction with trying to anticipate if wind is holding steady/rising/falling. I personally hold for wind in the reticle rather than dialing, so spotting your impact, noting the position in the reticle, then sending a quick follow up shot with the new wind hold is a good way to get a second round hit.

Now if your misses are high/low as well as left right then I'd start to look at ammo consistency. I don't think it's instability that's giving you any issues.
 
Try Berger's 105 VLD Target or Hybrid before you get too discouraged.

6BR CAN and WILL make accurate shots @ 1,000 yards, I've seen it done many times.

(Would I shoot one myself at that distance? No, it's one cartridge I haven't tried... yet.)

Those A-Maxes may be letting you down if their plastic tips are softening up from air friction heating then deforming or coming loose.
 
The difference in difficulty going from 700 yards to 1K is far more than the difference in 100 to 700. It's more in magatudes. Does your club have 800 and 900 berms? If so give them a try and make sure your loads not falling apart. Also give Berger 105's or the 107SMK a try. At 1K BC makes a big difference. In a 10 mph wind its about 10" less drift going from the AMax to the Berger or Sierra.
 
Using http://bergerbullets.com/ballistics/

Here is an example for you 6mm BR doing 2850 with 105 Hybrid at 70 degress/1000 ft elevation.

upload_2017-6-30_10-3-15.png

Since this wind is blowing at 90 degrees to target, we call this a full value wind.
I choose 10MPH to illustrate..

A "full value" wind is at 3 or 9 o'clock, in this case that is the 7MOA at 1000 yards.
A "1/2 value" wind is at blows from 5 or 7 o'clock.
A "7/8 value" wind blows from 4 or 2 o'clock.

In this example a 10mph at full value is 7.0 MOA... which implies a 1mph wind is 7/10 MOA !!!
If it is blowing at 10mph and lets off to 9MPH, you will miss by 7/10 MOA.

Now lets say you have a 10 mph "tailwind"... that is switching from 7 o'clock to 5 oclock....

At 7 oclock it is runs "half" value L to R... or 3.5MOA Left to Right
If it switches direction to 5'clock it is now 3.5MOA R to L....

That is a total movement of 7 MOA.

Tail/Head winds are the toughest to shoot in.


But if the wind is switching between 10 and 8 o'clock (Both "half value" direcdtions) there is no change in wind!!


F-Class shooters TRY to read the mirage direction and intensity to identify if conditions are the same or different.
Some are much better at others.

I really enjoy shooting a 6mm, I have several cleans at 800 and 900, but that extra 100 yards to 1000 makes a big difference.

Hope this helps.
 
I wouldn't worry about chasing a different bullet or load, a 105 Amax at 2866 fps is more than capable. I shoot a reduced velocity 6 Dasher load for practice sometimes and it does just fine at distance. Hornady 105 BTHP at 2800 fps, 950 yards no problem. I've had it out to 1225 yards hitting 70-80% on an IPSC target. Admittedly there wasn't much wind that day though. :)
 
If you missed the memo the red tipped AMax does have issues at 1000 with tips melting.
Berger makes some great 105 to 108 bullets.
Running a 105 vld it takes 27 moa.Lots of fun at 1000.
 
Wow, that's a lot to digest! I did not realize that the wind played such a big role as the bullet nears sonic speeds at 1000 yds. But it make sense now. It was mostly lateral movement, so it appears the bullet was performing well, but the wind was a greater factor. Lot's to learn now......

No wind flags at this range, and it's only steel past 200 yds. and the targets out to 500 are well protected. You shoot over these to hit the 750 and 1000 so wind kicks in after 500 making it harder to read.

I am shooting the 105 hybrid too, this week placing 5 in a .389 moa group at 300, and I still have more development to do, so it's looking like my next shoot at 1000 will be Bergers.

I also picked up a new batch of Hornaday 105 BTHP and 108 ELD Match to try.

Any comments?

Thanks for all the suggestions, and schooling, this really helps. You guys are the best!
 
Have seen 105-AMax from 6BR'a used at IBS1000 matches. From 6Dasher's, myself have shot 105-AMax bullets to 1000yds on many occasions, and once to 1760yd/1-mile with good stability (symmetric holes).
Donovan
 
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I have trouble shooting well at 1000, no matter the cartridge I shoot. Having said that, I believe that after about 600 yards the projectile has slowed down and still slowing down at an accelerated pace by this time. HIGH B.C. heavy bullets slow down at a slower pace than lower B.C. do. I believe that this allows the wind to "work on the bullet's flight path" for a L-O-N-G-E-R time, thus making lower B.C. bullets much more susceptible to the winds' push..
 
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