BC question

[RCMSTER]

So I bought some .257, 95 grain HHT bullets to shoot in my 257 roberts. After doing my load work-up, I settled on 43.5 grains of A4350, and according to Labradar, average muzzle velocity is 2914 fps with a SD of 15.6. When trying to plug the numbers in to my ballistics app, it's asking for G1 bc, but the only number I get off of Hammer is the G7, which is .196. Anybody know how to convert the G7 to G1? Thanks

 

[Zen Archery]

Good tool

JBM - Calculations - Drag Function Conversion

www.jbmballistics.com

 

[Zen Archery]

Weird that it's profiling modern bullet in G1… kinda old school.

 

[marksman1941]

So I bought some .257, 95 grain HHT bullets to shoot in my 257 roberts. After doing my load work-up, I settled on 43.5 grains of A4350, and according to Labradar, average muzzle velocity is 2914 fps with a SD of 15.6. When trying to plug the numbers in to my ballistics app, it's asking for G1 bc, but the only number I get off of Hammer is the G7, which is .196. Anybody know how to convert the G7 to G1? Thanks

What app are you using?

 

[lancetkenyon]

So I bought some .257, 95 grain HHT bullets to shoot in my 257 roberts. After doing my load work-up, I settled on 43.5 grains of A4350, and according to Labradar, average muzzle velocity is 2914 fps with a SD of 15.6. When trying to plug the numbers in to my ballistics app, it's asking for G1 bc, but the only number I get off of Hammer is the G7, which is .196. Anybody know how to convert the G7 to G1? Thanks

Can you not switch your app from G1 to G7???

 

[marksman1941]

You could play with this some and see if it matches your real world experience https://www.jbmballistics.com/cgi-bin/jbmgf-5.1.cgi

 

[RCMSTER]

What app are you using?

The app is called SBC v5.7. I like the ap. I don't know how to switch it from G7 to G1.

 

[RCMSTER]

Can you not switch your app from G1 to G7???

I see no options to switch from G1 to G7. Perhaps if I emailed the support they could tell me. Guess this is what happens when I switched from Strelok to this.

 

[lancetkenyon]

SBC?
Is this a dowloadable app on your phone?

 

[lancetkenyon]

Small Block Chevy 5.7?
You hit them with your car?

 

[RCMSTER]

SBC?
Is this a dowloadable app on your phone?

Yes. Supposed to be specifically geared for iPhones. It has 600+ reviews and holding at 4+ stars.

 

[biednick]

G7 is generally about half G1. That should get you close enough to true your muzzle velocity and get accurate results.

 

[Huntnpack]

Not scientific……but
According to my tape measure ….

1.9516 x .196 = .3825

Close……+ or -

Disclaimer: start low & work up.

 

[RCMSTER]

G7 is generally about half G1. That should get you close enough to true your muzzle velocity and get accurate results.

Thank you.