Interesting equation. Do you have a source?

Oh, and your 200g bullet now acts like a 200.6g bullet. And at 1:14" twist, it acts like a 200.4g bullet. I would not be too concerned while shooting.

 

I read the result in a book by Corner and then derived it myself. What if you are shooting 2 bore, 3,500 gr?

Btw, this only applies while in the barrel. Since this effect was present during load development, it is only valuable

to someone performing a mathematical analysis of the process.

 

If you are increasing reaction force due to the greater combined (linear and angular) inertia, there is going to be a corresponding friction increase as well.

 

Corner says that is is sufficiently small that to consider it would be "pedantic".

 

Very likely. I recently ran into something old in which estimates of energy lost to barrel friction were on the order of 10% of ME. It strikes me as high, and I've seen estimates as low as about a third of that, but even if I adopt that number, in 64XP-100's example, were looking at 0.02% of the total ME, or about half a foot-lb out of 2500 due to the greater twist rate.

 

...something old in which estimates of energy lost to barrel friction were on the order of 10% of ME..

I have been using 7% in my spreadsheets.

 

I have always wondered if the 1:7 twist rate I have on my .284" barrel was affecting muzzle velocity. After running the numbers the 175gr bullets are effectively 180gr bullets. The increase came out to be 3.24%. Seems to make sense to me if I'm understanding the equation.

 

I think you forgot to divide by 2 before squaring. In addition, you do not

have cylindrical bullets. You need to know the actual radius of gyration.

 

I did forget to divide by 2. Thank you