Bullet length to twist
02-23-2007, 01:20 PM
#1
Giant Nontypical
Thread Starter
Join Date: Nov 2005
Posts: 6,585
Bullet length to twist
I have been playing with several formulas that are supposed to give the length to caliber to twist ratio, I happened to know that at one time several of you were also doing this. I would be interested in knowing how our answers compare.
I am finally satisfied with my results and how they compare to actually shooting. I believe that using a 200 to 225 gr 40 cal bullet at around2250 fps or a 45 cal bullet at 275 to 300 grs @ around 2050 has the best potential accuracy for a 1-28 twist. I would like to know what answers you all have formulated. Lee
I am finally satisfied with my results and how they compare to actually shooting. I believe that using a 200 to 225 gr 40 cal bullet at around2250 fps or a 45 cal bullet at 275 to 300 grs @ around 2050 has the best potential accuracy for a 1-28 twist. I would like to know what answers you all have formulated. Lee
02-24-2007, 06:44 AM
#3
Nontypical Buck
Join Date: Feb 2003
Posts: 3,092
RE: Bullet length to twist
Lee, I've played with Greenhill formula variations as well as the online design program at Mountain Molds but only for bore-sized conicals. Neither yields an answer that's set in stone - seems like both will get you no better than close numbers for ideal twist rate (or bullet length).Seems to me that it's hard to "over stabilize" a bullet.
02-24-2007, 11:05 AM
#4
Giant Nontypical
Thread Starter
Join Date: Nov 2005
Posts: 6,585
RE: Bullet length to twist
Underclocked,while its quite easy to understablize a bullet and easy to detect the problem when it is extreme over stabilization is much more subtile and in the begining stages only opens the group. I think what happened with the very good 1-38 twist and the 1-20 twist are good examples. The 1-38 went by the way side because people insisted on trying to shoot long heavy bullets through it when its best with bullets under 250gr, mine will shoot nice tight groups with round ball and 90 gr of P. While the 1-20 should work well with long heavy bullets usually 300gr +. There really should be a point where you have max potential for one hole groups the thng that makes sorting all that out difficult is that the whip or vibration of the barrel also enters into it and since in a rifled barrel that is circular it makes a complete sepertae tuning problem. That makes it necessary to work up and down the powder ladder while not getting to far from the right velicity. The thing that makes it interesting is that after playing with the math I went out to the range and it worked for me know I would like for some one else that has done the same to varify it so I know its not a flukeLee
