Max effective range of 168 Eld M in 308?

[Stovetop535]

Curious what people have found regarding Hornady 168 Eld M ammo and the effective range?

Im shooting an AI AT chambered in 308 with a 20 inch barrel with a vortex razor on top. The gun shoots really well out to 600 yards, then from 600 and out doesnt group at all.

Last week we were shooting 2/3 scale torso targets, 100 500 and 725 yards.

500 yard target grouped very nicely. Dial up to the target at 725 and I can see impacts all aroud the target, both high and low followed by left and right.

I had 5 hits in a row, followed by 10 misses that were all over the place. Another accomplished shooter, who I consider a better long range shot than myself, had the same happen to him.

Is this possibly the result of the ammo and 20 inch barrel?

Thanks
Alex

 

[JMW67]

Curious what people have found regarding Hornady 168 Eld M ammo and the effective range?

Im shooting an AI AT chambered in 308 with a 20 inch barrel with a vortex razor on top. The gun shoots really well out to 600 yards, then from 600 and out doesnt group at all.

Last week we were shooting 2/3 scale torso targets, 100 500 and 725 yards.

500 yard target grouped very nicely. Dial up to the target at 725 and I can see impacts all aroud the target, both high and low followed by left and right.

I had 5 hits in a row, followed by 10 misses that were all over the place. Another accomplished shooter, who I consider a better long range shot than myself, had the same happen to him.

Is this possibly the result of the ammo and 20 inch barrel?

Thanks
Alex

Round may be going subsonic and destabilizing do you know your muzzle velocity I have not seen a 308 do this until further out but anything is possible

 

[Stovetop535]

Avg 2621 fps on a 40 degree day in Nebraska, approximately 1200 ft elevation

 

[JMW67]

1

 

[Stovetop535]

Yes. Sorry. Phone needs bigger numbers.

 

[okie man]

I was tearing up a 12" steel plate at 750yrds the other day with my 308. 168gn Hornady bthp at 2825fps out of a 26" barrel though.

 

[JMW67]

Yes. Sorry. Phone needs bigger numbers.

that is not the case then you should not be subsonic at that distance have you shot other rifles at this distance without this problem big difference between 500 and 725

 

[Stovetop535]

4dof showed the projected velocity of 1591 fps at 700 yds, which I thought would be fast enough to stabilize.

 

[Stovetop535]

That same day we brought out an AI 338 lapua and had no issues at 700. We were planning on going back to 1k but ran out of time.

I have shot the 308 one other time at 650 and 800 and had the same issues. Consistent hits and groups at 650 yds and no consistency at 800. Initially i thought it was me just having a bad day but now it has happened on two separate occasions above 700 yards.

 

[Bucklowery]

Mine really shines out to 600 on deer but I don't have problems with targets beyond that til subsonic. MV at 2550 that was my most accurate load though. Remington with 20" bull barrel 308. 168 gr amax 1-10 twist

Thanks

Buck

 

[ORCON]

What was the wind doing?

 

[Stovetop535]

6mph constant, occasional gusts up to 12 measured with a kestrel. We were shooting in a cornfield with a dense tree line to two sides (the backstop side and the side to our right, with a right to left wind.

 

[Possum Cop]

My experience with 3 different 20" barrels in .308 shooting 168 grain BTHP ammo. I shot hand loads in one of the rifles and factory Blackhills ammo in the other 2.

All 3 guns shot good groups out to 600 yards but started to open up around 700 but still were center of the target. 800 yards all rounds hit the target but sporadic and at 850 yards the bullets were going in the target sideways. I would assume that the rounds went transonic at 750 or so and subsonic at 8 to 850. This is not scientific, just my take on what I think was happening.

Severe instability can occur at transonic speeds. Transonic shock waves can cause increased drag and add asymmetry and unsteadiness to the air flow around the bullet which will cause the bullet to wobble and become unstable.

My 26" barrels didn't have these issues they grouped tight and hit the center of the 1000 yard F-Class rifle targets. I was shooting 175 grain hand loads in these 2 rifles.

Just my 2 cents.
Best of luck!

 

[Stgraves260]

Curious what people have found regarding Hornady 168 Eld M ammo and the effective range?

Im shooting an AI AT chambered in 308 with a 20 inch barrel with a vortex razor on top. The gun shoots really well out to 600 yards, then from 600 and out doesnt group at all.

Last week we were shooting 2/3 scale torso targets, 100 500 and 725 yards.

500 yard target grouped very nicely. Dial up to the target at 725 and I can see impacts all aroud the target, both high and low followed by left and right.

I had 5 hits in a row, followed by 10 misses that were all over the place. Another accomplished shooter, who I consider a better long range shot than myself, had the same happen to him.

Is this possibly the result of the ammo and 20 inch barrel?

Thanks
Alex
[/ Max effective range according to military is 800 meters. That's with a 24" barrel. You lost about 100 FPS with a 20" pipe. So 700 meters or 765 yards would be about max.