Differences in BC numbers on 180 hybrids

[bsumoba]

I've noticed different BC numbers on the same lot# of Berger 180 hybrids, 7mm. I also noticed that the twist rates seems to change. Old lot#'s used to be 9 twist, then went to 8 twist, then 9 twist, then back to 8 twist.

What gives?

 

[RDA72927]

That's a small issue. The real question is when did Berger start getting their labels from Laupa!! Can't seem to get the labels off the box cleanly.....

 

[Milo 2.0]

I do not know anyone at Berger, and am probably talking out of my butt, but BC testing equipment seems to get better every year, and having correct numbers only serves us all better.
As far the twist rates go, I'm going to say just a protectionism measure so they do not have to field calls as to why my bullet doesn't seem to work. 4-5 yrs ago, their stability factor was set at either 1.40 or 1.42, today the minimum is 1.50.
http://www.bergerbullets.com/berger-bullets-twist-rate-recommendations-by-eric-stecker-bryan-litz/

 

[KevinThomas]

Milo nailed it. It's just a bit of an update to reflect our most recent testing, and adjustment tweaks regarding twist recommendations. Bryan stays fairly busy trying to stay on top of this stuff in order to provide the most accurate BC info possible, and to make the best recommendations we can so the customer gets the optimal performance out of the product. His leaning towards a somewhat higher SG recommendation than we've accepted in the past is just a matter of evolution as the game (and the technology) has become more refined.

 

[bsumoba]

Milo nailed it. It's just a bit of an update to reflect our most recent testing, and adjustment tweaks regarding twist recommendations. Bryan stays fairly busy trying to stay on top of this stuff in order to provide the most accurate BC info possible, and to make the best recommendations we can so the customer gets the optimal performance out of the product. His leaning towards a somewhat higher SG recommendation than we've accepted in the past is just a matter of evolution as the game (and the technology) has become more refined.

So, will BC and twist rate recommendations change as each lot# is tested ?

 

[KevinThomas]

No, it's just an update and not a lot by lot change. Bryan is just trying to give you the most accurate info we can, to give you better downrange results with the ballistics apps out there. After all, in the change the OP cited, we're looking at an adjustment of .006 on the G1, and .004 on the G7. In our stability calculator (found on our website at www.bergerbullets.com) you'll see the trend toward slightly faster twists. The original twist recommendation will work, but the revised recommendations will give you a slightly better SG. The calculator will give you and indication of how much the BC is compromised when you're running SGs in the 1.4-1.0 range, against those that are 1.5 or better. Never hurts to have a little added insurance in the field.

 

[Ned Ludd]

The BCs of all bullets within a single box are not even the same. The BC values will vary by a small amount depending in part on the OAL of a specific bullet. Minor Lot-to-Lot variance is also to be expected, as is variance in the [average] BC values listed on the box as new Lots are tested from time to time. As long as the changes remain [relatively] small, there's no need to be concerned.

 

[dcali]

Either way, they're most likely wrong at that level of precision. Berger's to be commended for putting the effort into keeping the numbers updated with the best available information, but there's only so good it can be. It probably wouldn't be a terrible idea to report BCs with only two decimal places.

 

[KevinThomas]

The BCs of all bullets within a single box are not even the same. The BC values will vary by a small amount depending in part on the OAL of a specific bullet. Minor Lot-to-Lot variance is also to be expected, as is variance in the [average] BC values listed on the box as new Lots are tested from time to time. As long as the changes remain [relatively] small, there's no need to be concerned.

Spot on. Many don't seem to realize this, but in doing BC testing, you wind up with the same range as you do when chrongraphing for velocity; Highs, lows, extreme spreads and a standard deviation. The resulting BCs are the average of the testing. As production methods improve, like everything else in this field, we start to see those extreme spreads narrow, the highs and lows become closer together, and the average become far more meaningful.