I have this formula to determine best twist rate for bullet. TR= C* D2/lL I used 150 for C used .224 for D2 and .790 for L I keep getting 84 for answer what am I doing wrong? I'm wanting it for a .224

Ok didn't know that was the weight , I used 55 for the 150 and still not coming up with a Right answer. Here's what I'm doing TR =55 * .224(2) divided by .790 * = multiply. Don't have a multiply sign on keyboard. I will use the revised one and see if r helps Thanks

thanks. didn't read that far! was thinking it had something to do density. how do you find the SG of a particular bullet? is this information readily available?

I've seen from 10.9 to 10.7 as the benchmark for jacketed bullets. Another example of it being used; JBM Ballistics, Drag/Twist.

What weight bullet are you looking for? 55 gr in a223 needs a 1:12 twist you can go as fast as a 1:8 twist but that is pushing it...

Ion loading up some 60g nosler balistic tip spitzers I'm shooting this bullet from my 1 *8 twist M&P 223 16in barrel. This 24g of varget is nearly filling it up to the neck?? Is it supposed to? Thanks

That's about right. Most of all my loads compress the powder a touch. Except for the garand. It's loaded weak so you hear the powder bouncing around if you shake it. Here is another formula you can try for twist rate/bullet weight calc. “military type bullet measuring .647" in length. The bullet diameter is .224", which divided into the length of .647" gives 2.89 calibers long. Dividing 2.89 into 150 yields a figure of 51.90 or an ideal twist rate of one turn in 51.90 calibers. Multiply 51.90 by the bullet diameter (.224") equals one turn in 11.63" for this particular bullet” /wa/viewBook?id=411474161