I didn't know where to post this, so I threw the dart and took a chance. Staff, please move this to appropriate section, I don't really know where it belongs.
I just picked up a used H&R Handi-rifle in .223. The twist rate is 1 in 8 1/2. I looked up the Greenhill formula, but the best I can determine, that formula dictates twist rate required for bullet length, not the other way around.
I do understand that I'll need a heavy bullet for this fast twist. How do I determine the weight I need based on the length required? Right now, I'm stumped 'cause I don't know how to determine either one.
Thanks, fellas.