Berger Bullet stability?

edge

Well-Known Member
Joined
Nov 4, 2005
Messages
1,088
A while back a member here sent me the Don Miller Stability Formula applet, thank you:)

If I go on the Berger website I see that 308155V requires a 14 twist barrel.

If I plug in the info on that bullet from the Berger website into the Don Miller program:
@40 degrees and 2900fps

The program shows a stability of only 1.09 and that it should really have a 12.4 twist for optimum stability.

I currently shoot a 14 twist and a bit faster MV with good accuracy but I am shooting in 60 degree temps!

I am a bit concerned about cold weather shooting with this setup now, should I be?
I may see temperatures into the single digits on occasion which will drop my velocity a bit and with high pressure I may be less than 1.00 according to the program!!!

I would assume that Berger anticipates all temperature extremes with their recommendation of 1:14 twist minimum, but............


edge.
 

elkaholic

Official LRH Sponsor
Joined
Dec 4, 2008
Messages
9,316
Location
hauser, id.
Edge......contact Bryan Litz at Berger and he should be able to answer all your questions. By the time you get this, he may even have an answer on this forum as he is a sponser. Good luck.....Rich
 

BryanLitz

<b>Official LRH Sponsor</b>
Joined
Mar 8, 2007
Messages
633
edge,

Sorry for not replying to your question sooner.

The Miller stability formula is based on 'nominal' projectiles that have 'nominal' shape and balance. If a bullet is too far away from ordinary in some way, it can cause the program to have some error.

The thing that's special about the 155 VLD is the large void in the nose. This will affect the balance/mass distribution in a way that is favorable for stability. In particular, the ratio of transverse to axial moments of inertia is lowered by the short core.

Rest assured that even though the Miller stability formula predicts instability for this bullet in cold climates, the bullet will be jut fine in the 1:14" twist.

When calculating the recommended twist rates Berger uses a different program that's more sophisticated (much less user friendly) to more accurately calculate the bullets stability requirements taking into account all the details of the bullets construction. The error in the Miller formula (when there is error) tends to be conservative which is good. It would indicate a faster twist than you necessarily need, so it will keep you out of trouble.

Hope this answers your question,
-Bryan
 

edge

Well-Known Member
Joined
Nov 4, 2005
Messages
1,088
Thanks to both of you :)

Bryan would that apply to plastic tipped bullets too, such as the Accubond, SST, and others?

Sorry to be a pest, but would the Accubond with the thick copper jacket and base be more or less stable if it had the identical shape as the Berger VLD?

Since I am being a pest, can you suggest a program that works well?

Thanks again for your replies.

edge.
 

Trending threads

Recent Posts

Nightforce has great tracking capabilities, they are rugged, a bunch of elevation, holds zero forever, and reticles are designed for long range shooting. So if you are looking to shoot long distances constantly, then you need a scope that can take the abuse. -- gilmillan1


Culture Of Excellence At Nightforce Optics
By Len Backus

A high level of quality both in production and in service. Read More


Nightforce is such a solid combo of reticle, available elevation, glass that is good enough to shoot at the longest range you can dial. Nightforce has bullet proof construction that can handle the incidental horse rolling or some other rodeo action. -- bigngreen


Nightforce ATACR Scope Review
By Jeff Brozovich

The new NightForce ATACR is for sure a top choice for any long range shooter. Read More


The total package. Nightforce is the best I have used as far as turret feel and solid detents. I have never had one that didn't track right on and always return to zero. Nightforce NXS is the best value for everything I need. -- Broz


Nightforce Velocity 1000 Reticle Review
By Scott Shreve

I think Nightforce knocked it outta the park with this reticle! Read More

NightForce


Top