Berger 6mm 105gn VLD hunting. G1BC 0.545
Berger 6mm 105gn VLD Target. G1BC 0517

If this is true then I might have to start using the VLD hunting pill for F-Class instead of the Target pill.

Thanks for clearing up the asterisk. Appreciated!

Comment and interesting finding…

Comment: Not trying to be picky, but the definition of “optimal” is “best or most effective” (Merriam-Webster dictionary). “Best” and “Most” indicate “whatever” you are considering will not be improved by varying from that “value”. I suggest a more appropriate column heading would be, ” BC impacted if twist slower than”.

Interesting finding: Berger’s SG calculator has gone well beyond determining whether the projectile will be “stable”. That tool also calculates the impact on BC – to the point of recommending a specific minimum faster twist if the calculated SG is not at least 1.5. [So the user is not simply “stuck” with the static “optimum” value in the published table.] An example, I selected the Berger 338 Cal 300 gr Hybrid OTM Tactical (33109) and varied the muzzle velocity from 2800 (SG = 1.50) to 2650 (SG = 1.47). With the 2650 velocity the calculator ALSO displayed:
Bullet BC (G7): .421
Adjusted BC for 1 in 10.5″ Twist: .417
Your BC is being compromised by: 1%
Minimum twist recommended: 1 in 10.3″

Now that, IMO, is worthwhile info! [And it shows that “optimal” is not always optimal. Also, regrettable, it also shows that the column titled “Minimum Twist Rate (of faster) also needs some help. For this example it reads 1:12″.]

Thank you Bryan and Berger!

Neil,
The twist requirements that we provide are conservative so that they will work in all scenarios. Furthermore, the stability formula used is especially conservative for flat base bullets.

The minimum twist requirement is the minimum required to achieve optimal precision. However the minimal twist requirement does not produce maximum BC. In order to fully stabilize the bullet and achieve maximum BC, you need the optimal twist or faster. Short range Benchrest shooters who choose flat base bullets typically are not concerned with maximizing BC, so the minimal twist is more applicable. However,this calculation of the minimum twist is especially conservative for flat base bullets.

The article linked in the bulletin above explains where we are coming from with our stability requirements. Here’s the link to that article again

http://www.bergerbullets.com/the-state-of-the-art-in-rifle-bullet-stability/

The important thing to understand is that you can achieve enough stability for full precision with a bullet, and not be maximizing its BC. You need a faster twist to realize full precision and BC. If you don’t care about BC, then you can get away with a slower twist and less stability. The complication is that you’re always in a different environment and shooting bullets at different speeds. So it’s very difficult to determine what conditions a manufacturer should recommended twist rates for. If we are conservative and base our recommendations on the worst case scenario, then the twist rates we recommend will not be realistic for most average conditions. However if we base our recommendation on average conditions, then there will be some cases which the bullets won’t fly well. The best thing to do if you want to understand the stability requirements of your specific bullet in your environment, is to use the Berger stability calculator and decide where you want to be on the stability spectrum. And to reiterate, the stability calculation is very conservative for flat base bullets.

We understand that shooters appreciate simplicity. However, there are a great deal of rifle shooters who choose Berger bullets, who are interested in maximizing performance and understanding the details of their shooting. We choose to support these shooters with a higher level of information, and supporting educational materials to explain the realities of spin stabilized projectile flight.

-Bryan

1. Why the asterisk (*) without any explanation of what the * means – does it mean anything? [Same problem as prior, not fixed here.]
2. BOTH “optimal” and “or faster” – is “faster” the same, less, or more “optimal” than “optimal”?

Berger/Bryan – please unconfused us.