Before I start, please don't take this as a negative attack or criticism of one companies product by another company. This is just my reaction to a situation that I believe deserves some careful inspection.
The drop data for this bullet results in a G1 BC of 1.1. Several people including myself have run the numbers and come up with this figure. Let's take a second and reflect on what a BC of 1.1 means for a 265 grain .338 caliber bullet.
The Ballistic Coefficient is a bullets sectional density divided by its form factor.
* Sectional density is bullet weight in pounds/diameter squared.
* The form factor is a multiplier that relates the drag of the bullet to the drag of some standard projectile. For this example, I'll stick with the G1 standard projectile.
The sectional density part of the BC is dependent on weight and caliber, whereas the form factor is only related to the bullets profile. In other words, a 90 grain .224 caliber bullet and a 300 grain .338 caliber bullet can have the same form factor, but will have drastically different sectional densities.
Here are some examples of sectional densities and form factors for some well known bullets:
22 caliber 80 grain Sierra Match King
Sectional Density = 0.228 lb/in^2 (it's = 80/7000/.224^2)
G1 form factor = 0.554 (measured average from 3000 fps to 1500 fps)
G1 BC = 0.228/0.554 = 0.412 lb/in^2
6mm 115 grain Berger VLD
Sectional Density = 0.276 lb/in^2
G1 form factor = 0.501
G1 BC = 0.551 lb/in^2
6mm 115 grain DTAC
Sectional Density = 0.276 lb/in^2
G1 form factor = 0.511
G1 BC = 0.540 lb/in^2
6.5mm 140 grain Berger VLD
Sectional Density = 0.287 lb/in^2
G1 form factor = 0.482
G1 BC = 0.595 lb/in^2
6.5mm 142 grain Sierra Match King
Sectional Density = 0.291 lb/in^2
G1 form factor = 0.495
G1 BC = 0.588 lb/in^2
7mm 162 grain Hornady Amax
Sectional Density = 0.287 lb/in^2 (same as 6.5mm 140 grain bullet)
G1 form factor = 0.479
G1 BC = 0.599 lb/in^2
.30 caliber 190 grain Sierra Match King
Sectional Density = 0.286 lb/in^2
G1 form factor = 0.543
G1 BC = 0.527 lb/in^2
.30 caliber 190 grain Berger VLD
Sectional Density = 0.286 lb/in^2
G1 form factor = 0.502
G1 BC = 0.570 lb/in^2
.338 caliber 300 grain Sierra Match King
Sectional Density = 0.375 lb/in^2
G1 form factor = 0.494
G1 BC = 0.760 lb/in^2 (advertised average BC)
Take a look at the G1 form factors of these bullets. They vary from a low of 0.479 to a high of 0.554 with an average of 0.507. Remember, lower is better. The form factor is a multiple of each projectiles drag compared to the G1 standard (short nose, flat based bullet). So a bullet with a form factor of 0.500 has 0.500 times the drag of the G1 standard. A bullet with a form factor of 0.600 has more drag, etc.
I've deliberately selected relatively low drag bullets for the 9 examples above. G1 form factors can easily go over 0.6 for lead tipped, flat based bullets. The lowest G1 form factor I've ever measured on any bullet is 0.456. This was a 6.5mm VLD type bullet made by an individual in PA.
This information gives you a sense for what G1 form factors are, and what you can expect their values to be.
Now let's consider the 265 grain .338 caliber bullet.
This bullet has a sectional density of 265/7000/.338^2 = 0.331 lb/in^2.
In order for this bullet to have a G1 BC of 1.1, it would have to have a G1 form factor of 0.301!
Once again, out of the 100's of bullets I've tested for BC, the lowest G1 form factor I've ever observed is 0.456. The average form factor of the 9 popular long range bullets above was 0.507 with a range of +9% -5%. A G1 BC of 0.301 is 59% less than the average.
Now let's take a step back.
I know these bullets have aluminum tips that are longer and sharper than conventional tips which will reduce their drag. A drag reduction of 10% to 15% is certainly believable, even 20%... maybe. But 59%?
Increasing nose (ogive) length reduces drag about 12% per caliber, meaning that for every caliber the nose is lengthened, drag is reduced by 12%. From the image in post #18 of this thread, the aluminum tipped bullet (I realize it's not the 265, but assume it's representative) appears to be at most 3/4 of 1 caliber longer than the conventional bullet. This means it could reasonably be expected to have 8% less drag (8% lower form factor).
Is it possible to have a bullet with a G1 form factor of 0.301 (59% lower than average long range bullets)? Maybe, probably, if it's long enough, and this is the final unsettling observation.
One thing is for sure. IF it is possible for a bullet to have a G1 form factor as low as 0.301, it would have to be extremely long. As we all know, extremely long bullets require faster than standard twists yet this bullet is stable in a standard 1:10" twist.
We all arrived at the 1.1 BC from the same drop data. As much as I don't like to criticize others for gathering and sharing information, I'm afraid I have to suggest that perhaps an error was made in this case of collecting the drop data. It simply implies an impossible form factor.
Take care,
-Bryan
Lightvarmint, why not send a few bullets to Brain and then we will have an accurate BC number derieved by shooting to 600 yards with equipment designed for such measurement.
Brain, I believe will gladly test theses bullet and report the truth about the BC numbers
Brain has in the past given out the BC numbers that he has tested no matter who manufactured them.
I see that you are afraid that the actual BC testing equipment will show that the bullets do not defy the Laws of Physics and are not magical.
All your double talk will not change the fact that you are afraid to have them tested by a very reputable individual, with the equipment to do so over a 600 yard spacing
JWP,
Every bullet shot is being tested by the end user.
James