I've used the Berger calculator, but it is not using the Miller formula. From what I can tell, Berger is primarily interested in calculating the loss of BC from their calculated Sg.
If I put a reasonable muzzle velocity of 3200 fps into the Berger calc at 5000 feet with a temp of 0 deg. F, I get an Sg of 1.28 which indicates I would be losing 7% of the BC. Instead of a BC of .468, I'd be getting .437 -- still better than Barne's 120 grain TTSX at .412
I won't know without testing, but I don't believe I'd get bullets keyholing under the above conditions. What I don't know and can't easily test is what I'd see with terminal performance.
Using the Miller formula under the same exact parameters - same bullet, same specs, 5000 feet and 0 deg. F, 3200 fps -- I get an Sg of 1.752. If I make conditions worse, 4000 feet, -5 deg. F, I still get a Miller-formula Sg of 1.666
Stability | | | |
Input Data | | | |
Caliber: | 0.264 in | Bullet Weight: | 127.0 gr |
Bullet Length: | 1.402 in | Plastic Tip Length: | 0.199 in |
| | | |
Muzzle Velocity: | 3200.0 ft/s | Barrel Twist: | 9.0 in |
| | | |
Temperature: | -5.0 °F | Pressure: | 25.37 in Hg |
Output Data | | | |
Stability: | 1.666 | | |
I'm not just wanting to argue calculator results. I can see the Sg results for myself. The question is: how will Sg affect terminal performance?
According to Hammer, they're essentially saying that I need an Sg of 1.9 to get good terminal performance with their bullets -- they say a Miller-formula Sg of 1.5 at sea-level, which would result in a Miller-formula Sg of 1.9 where I live (and even higher where I hunt).
If that's the case with Hammer bullets, what kind of Sg would I need to expect good performance from expanding bullets like TTSX, LRX, CX?