6mm. BR. Group Size @ 300 meters.

M

muzzle flash

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Okay I got a rifle with quality tube in 1/8 twist-put a burris 8x32 on it. Started shooting at 300 meter's with 105 amax. I shoot 5 round group's and have yet to shoot a clean group. I always send at least 1 round somewhere out of the group so I measure a 4 round group outside to outside. I shot 5 groups and had the barrel warmed up good. largest group went 1.436" and smallest went .897" at 300 meter's. If I added the flyer's I would have been into the 3" No wind but some mirage present.
Now I am not real impressed on the burris (just not as sharp and parallax adjustment is kind of a pain). Now I am fairly happy with this but my groups alway's land to one side or the other of the 1.5" dia. x ring.
How does this compare to you guy's with experience at shooting out to 300 meters??? Should I expect better result's?? THANKS.
 
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muzzle flash said:
Okay I got a rifle with quality tube in 1/8 twist-put a burris 8x32 on it. Started shooting at 300 meter's with 105 amax. I shoot 5 round group's and have yet to shoot a clean group. I always send at least 1 round somewhere out of the group so I measure a 4 round group outside to outside. I shot 5 groups and had the barrel warmed up good. largest group went 1.436" and smallest went .897" at 300 meter's. If I added the flyer's I would have been into the 3" No wind but some mirage present.
Now I am not real impressed on the burris (just not as sharp and parallax adjustment is kind of a pain). Now I am fairly happy with this but my groups alway's land to one side or the other of the 1.5" dia. x ring.
How does this compare to you guy's with experience at shooting out to 300 meters??? Should I expect better result's?? THANKS.
Click to expand...

Well with my box stock Rem 700 PSS in .308 Win.( before beimng rebulit) I was able to get 5 round groups that fit inside a quarter, dead center at 300 meters from prone using a bipod (this is when I am shooting a lot).

I would be happy with .5 MOA from any rifle.;)

SKBY.
 
Have you done your ladder testing and powder experimenting yet? That flyer is questionable. It should not be out that far. I usually find my flyer out about .500" at 300m. Even that will break you in any competition. There is some merit in the thought of experimenting using 15 shots to measure group size, Its really the unexplained flyers that cause the problem.:confused: Ive heard of some guys testing with only 3 shots? However if they really are looking for the absolute smallest group, its hard to beat 1..???:cool:
 
I agree with what has been said. You need to be thinking in terms of some serious load development including powder and seating depth. There are a lot of variables you didn't mention ( which powder, brass, bullet velocity, fire formed or not, etc.) or it could be as simple as the scope or its mount. The other thing is that an 8 power scope for that sort of shooting is not really optimal.

What is it doing at 100?
 
I am sure that you would have reviewed the basics to debug the rifle. Since you are already shooting some very small groups, let's look at something different.

When is the flyer? Same rd in your group or random?

Where does the flyer land? Same general direction or random?

How close to max pressures are you running? Flattened primers?

In the heat of summer, it is not uncommon for me to go over the 'pressure' sweet spot of the barrel. This shows up as unexplained flyers.

By backing off the load 2 to 5 tenths, all is back to normal.

If it continues, how many shots have you had with this brass? Maybe its time to anneal the necks...

Jerry
 
Brass is lapua on its third firing,I am stuffing 28.8 gr. of varget with a 105 gr. hornady into the case. The flyer's go out of the group at about 7 oclock. Am not sure which one out of the 5 round string takes a walk. Primers are flat but not excessively. I have not put any rounds over chrony because my chrony is suffering from a perforation dissorder. I most likely was shooting with a tube that was warmned up to much also the scope was a burris 8x32 x50, 30mm. black diamond which I am sorry I bought comparing it to the leoupold. 100 meter 5 round groups are basically 1 hole about 1/2". All shooting done with front and rear rest. The mount I originally started with was a well made farrel/badger type but it had 40 moa slant. While this will work for you guys shooting way out there I found I could not get a 100 meter zero (shot 6"high). I ended putting a cheasy cheap weaver base on it for now. THANKS.
 
Assume the optics and mounts are not drifting.

I would work up your load at 300m starting 6/10 gr under and going 1/2gr over your present amount if that is not too high in pressure. Go up in 2 tenths.

Stringing can be part of your problem. Also, variation in brass volume may be pushing you over max.

Shot and mark each shot. If there is a flyer, mark that brass. The next time you shoot, if that brass causes another flyer - get rid of it.

Just watch the conditions as 300m is far enough for wind to push you around.
Jerry
 
Mystic.* is a smart guy and I have listened to many things he has said. I would only point out that every 6BR shooter I know using 105's , including myself considers 2850 fps to be a sweet spot for velocity and accuracy.

I don't know of anyone using less than 30 grains of Varget with Lapua brass to get that. I use 30.5gr. I concede that every gun is different, and I am all for the least powder and velocity to get the job done with the BR, but I would bet money that if your brought the velocity to somewhere near 2850 you'd see a difference.

I would also encourage you to post the same question on the 6mmbr.com forum; For some comparison, here is the load they suggest starting with for 105's: (They tend to be a bit snobbish and don't list a-max's specifically, but i use them with good results too)

Std Case, 105gr Lapua Scenar, 30.0gr Varget, CCI BR4, 2870 fps
Std Case, 105 Berger VLD, 31.0 Reloader 15, CCI BR4, 2975+ fps
Std Case, 105gr Berger VLD Moly, 31.0 VV N540, CCI 450, 2900 fps.
 
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