223 1/9 tw with 80,5 gn Berger

L

Liseo

Member
Hi

In my custom rifle with 1/9 tw krieger, I tried the Berger 80,5 grains Full Bore at 2891 fps.


Per Berger barrel tw calculator, I have a SG of 1,15, what means the stability is "marginal"


Anyway, using bipods, I get groups in the .30" and .40" at 110 yards, without any keyholes, for 4 five shoot groups.

So, what effects for this situation ( marginal stability) to get good groups? Some unexpected flyers or what? The groups will open beyond normal at longer ranges?



Excuse for language errors...
 
Liseo

Return to the Berger web site and look at the Target bullets.
The 80.5 gr bullet listed is for a 1:8 twist barrel.
You might try the 73 gr or the 70 gr Berger bullet to solve you problem.
Good luck and let us know how this works out for you.
Centerfire
 
5 shot groups measured center to center??? 0.30" to 0.40" "Krieger barrel custom chamber" Correct.
That's nice.
they might have used a longer barrel, different twist, different primers, different powder, etc.
The key I think is the custom rifle.

For standard Benchrest Short Range.
1/14 tw 21.75" Krieger Custom chamber with a DS reamer, 6 PPC, 65-70 custom bullet, etc. There are 3 different nodes for a tight group. 3 loads.
Exspect 0.30 -0.50" groups at 200M.
My question? What is the problem?
Go shoot some coyotes.
 
Hi Liseo,

.3"-.4" at 110 yards is good shooting off a bipod. The faster you spin a bullet the greater bullet imperfection opens groups, so the most accurate twist rate is the slowest rate that will keep your bullets stable in the air density you're shooting in. Since Berger doesn't know what velocity, temperature, humidity and altitude you're going to be shooting in, the recommended barrel twist must assume worst case conditions to prevent customer frustration. If you shoot your combination in very cold conditions or at lower elevation you may see a loss of accuracy from instability. Berger bullets are known for their quality so you would probably see very little to no decrease in accuracy if you shot the same combination substituting a 8" or even 7" twist barrel except in the most controlled environment.

Greg
 
Greg and others


With Berger 73 grains BT I manage to get groups in the .25 to .30 at same distance (110 yards)


as I intend to shoot at 330 yards in a competition this weekend, I was wondering if it was worth losing a little precision in exchange for better performance in the wind.( This range is know for windy conditions)
But as ever used these heavier bullets at that distance, I wondered if the fact of compromised stability cause some unexpected flyers.


As a side note, I already got a Krieger 1/8 tw for those heavy bullets( will fit soon)



Thanks again
 
Liseo,

Take both loads with you, If the wind lays down, shoot the more accurate 73's. If it blows, shoot the 80.5's. And you can switch during the match if the day starts out quiet and picks up over time. Even if it's windy you can do excellent work with the lighter, more accurate bullets at 300 meters if you time your shots to go downrange during like conditions. Wind variations will generally reveal a rhythm. Pay attention and exploit that fact by choosing when to shoot your string, not necessarily as soon as the fire for record command. The same strategy applies at 600 and 1000 but you will almost always benefit from the higher BC of the longer, heavier bullet.

Greg
 
Liseo said:
Anyway, using bipods, I get groups in the .30" and .40" at 110 yards, without any keyholes, for 4 five shoot groups.

So, what effects for this situation ( marginal stability) to get good groups? Some unexpected flyers or what?
Click to expand...
It may simply be the maximum capability of your action/barrel combination. Shooting off a bipod is not helping either.
 
You must log in or register to reply here.
Back
Top