# 245 berger bullets

##### Well-Known Member
My question is why not just make all programs for boat tail bullets use the g7 math to calculate trajectory its all smoke and mirrors

The answer is because its not smoke and mirrors. Trajectory prediction programs reference models, and bc’s are a factor of your chosen bullet to that model. If you were right about what bc’s actually are, it would be as simple as to “make all programs us the g7 math.” Unfortunately you are wrong.

If anyone is still paying attention,
the G7 BC of the Sierra 230 pointed is .401

The berger 245 is .413

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#### TwistedFox

##### Well-Known Member
The answer is because its not smoke and mirrors. Trajectory prediction programs reference models, and bc’s are a factor of your chosen bullet to that model. If you were right about what bc’s actually are, it would be as simple as to “make all programs us the g7 math.” Unfortunately you are wrong.

If anyone is still paying attention,
the G7 BC of the Sierra 230 pointed is .401

The berger 245 is .413
The g7 program math is designed to work with g7 #'s that are derived from g1 #'s did the bullet change based on the model you used? no it has not its still the same bullet. You just applied a different drag number to it and then ran a different math program

#### richhymas

##### Well-Known Member
I think it is worth stating the obvious to clarify for the readers. The G1 calculation assumes an ideal bullet with a flat base. The G7 calculation assumes a boat tail shaped ideal bullet. You could take the actual dimensions of your bullet and calculate a form factor to see how closely your bullet represents the ideal bullet used in the formula. You should then use the formula that most closely resembles your bullet.

it is true that the G1 and G7 BC for a given bullet can be calculated from one another, however the user needs to decide if his or her bullet of choice more closely resembles the ideal flat base bullet (G1) or the ideal boat tail bullet (G7).

#### TwistedFox

##### Well-Known Member
I think it is worth stating the obvious to clarify for the readers. The G1 calculation assumes an ideal bullet with a flat base. The G7 calculation assumes a boat tail shaped ideal bullet. You could take the actual dimensions of your bullet and calculate a form factor to see how closely your bullet represents the ideal bullet used in the formula. You should then use the formula that most closely resembles your bullet.

it is true that the G1 and G7 BC for a given bullet can be calculated from one another, however the user needs to decide if his or her bullet of choice more closely resembles the ideal flat base bullet (G1) or the ideal boat tail bullet (G7).

View attachment 215585
Agreed

##### Well-Known Member
The g7 program math is designed to work with g7 #'s that are derived from g1 #'s did the bullet change based on the model you used? no it has not its still the same bullet. You just applied a different drag number to it and then ran a different math program
An issue with accurately measuring flight characteristics of a bullet is that any mathematical model must differentiate between the many types of bullets and shapes; bullets of different shapes yield different drag curves, and cannot be modeled by a single formula. Because of this, several different drag curve models have been standardized for common projectile types, and are shown below

This is a quote from the kestrel article posted by rich, with whom you just agreed.

I dont know how to explain this to you in any other way. Im done arguing. I simply have much better things to do.

#### kaseyfied

##### Well-Known Member
An issue with accurately measuring flight characteristics of a bullet is that any mathematical model must differentiate between the many types of bullets and shapes; bullets of different shapes yield different drag curves, and cannot be modeled by a single formula. Because of this, several different drag curve models have been standardized for common projectile types, and are shown below

This is a quote from the kestrel article posted by rich, with whom you just agreed.

I dont know how to explain this to you in any other way. Im done arguing. I simply have much better things to do.
Obviously not but got some good info

Kasey

#### Bravo 4

##### Well-Known Member
My friend tested 300smk in wet phone books and they are very random. Some expanded, others simply flattened lengthwise, while others looked like they could be reused. We used them out of an edge for years on elk and deer. Excellent on steel, horrible on animals even when hit in the boiler room. Easy to load accurately for sure. The Berger 300 came out and we switched but werent as easy to load develop. Just our experiences.
I’ve had the exact opposite experience with the 300 SMK. I have ran them out of a .338 Edge or RUM for over 15 years and they have smashed everything I’ve hit with them from deer to elk, real close to over 1400. Like the Bergers, you have to make sure the tips are open and free of anything that may clog it up. Actually I have had better terminal than with the 300 Bergers.
I had not so good results with 7mm versions of the SMK and just ok results with the .308 versions. Not all bullets of the same design/name act the same in different calibers/weights.

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