how fast is to fast-Berger VLDs

[oldmossy]

I'm shooting 180 grain vlds in my 7mm rum at 3300 fps. I can't get it to shoot any better than 2" at 200 yds. I have varied my loads by as much as 4 grains, and have come as far as .060 off the lands.I was told that for the barrel twist that I have, I need to be shooting the 168 vlds.
I've heard that the vlds started coming apart anywhere from 3150-3400 fps. Just wondering if anyone could shed any light on this for me.
And while we are on the subject of berger vlds. At what velocity does the bergers start to stay together when impacting an animal. I'm worried about shooting an animal at any close distances. I'm hunting an area where my "normal" close shot is going to be around 600yds. But who knows whats going to happen while hunting.

[Broz]

If you push the 180's or 168 over 3250 in a barrel twist faster that 1 in 9 you will probably start to see the problems. We run them at 3150 to 3200 in 9 twists all the time with no issues. We have taken game as close as 100 yards and less with 9 twists at 3200 and all was good. But expect a very very dead animal with a big hole at these distances. This does not bother me as I never save ribs anyway.

Jeff

[load]

its not really coming apart but what happens with vld designs over 3000 fps is that a secondary shock wave starts appearing at the shoulder at around 3000 to 3200 fps. the longer the nose the the sharper the shoulder the worse the shock wave. This shock wave can do several things. 1 change bc unexpectantly with varying effect for atmospherics, 2 change the trajectory of bullet flight and 3 cause the bullet to loose stability.

[bigngreen]

Originally Posted by load

its not really coming apart but what happens with vld designs over 3000 fps is that a secondary shock wave starts appearing at the shoulder at around 3000 to 3200 fps. the longer the nose the the sharper the shoulder the worse the shock wave. This shock wave can do several things. 1 change bc unexpectantly with varying effect for atmospherics, 2 change the trajectory of bullet flight and 3 cause the bullet to loose stability.

Why does slowing the twist or just adding a few thou to the jacket ,with no exterior design change, help if this is what was happening?

[oldmossy]

thanks for the info

[meatyrem]

Originally Posted by oldmossy

I'm shooting 180 grain vlds in my 7mm rum at 3300 fps. I can't get it to shoot any better than 2" at 200 yds. I have varied my loads by as much as 4 grains, and have come as far as .060 off the lands.I was told that for the barrel twist that I have, I need to be shooting the 168 vlds.
I've heard that the vlds started coming apart anywhere from 3150-3400 fps. Just wondering if anyone could shed any light on this for me.
And while we are on the subject of berger vlds. At what velocity does the bergers start to stay together when impacting an animal. I'm worried about shooting an animal at any close distances. I'm hunting an area where my "normal" close shot is going to be around 600yds. But who knows whats going to happen while hunting.

You never did mention what twist your barrel has?

[meatyrem]

Originally Posted by oldmossy

I'm shooting 180 grain vlds in my 7mm rum at 3300 fps. I can't get it to shoot any better than 2" at 200 yds. I have varied my loads by as much as 4 grains, and have come as far as .060 off the lands.I was told that for the barrel twist that I have, I need to be shooting the 168 vlds.
I've heard that the vlds started coming apart anywhere from 3150-3400 fps. Just wondering if anyone could shed any light on this for me.
And while we are on the subject of berger vlds. At what velocity does the bergers start to stay together when impacting an animal. I'm worried about shooting an animal at any close distances. I'm hunting an area where my "normal" close shot is going to be around 600yds. But who knows whats going to happen while hunting.

The Berger site lists the 180gr to have a 9 twist.
And the 168gr to have a 10 twist