The way Tim explains taking a twist measure is an excepted method and it works well..
There are four criterias that determines the rate of twist, the most important is the length of the bullet. The longer the bullet the more twist you need.
Next is the MV of the bullet which will give the bullet rotational stability. More speed will require less twist but not as much as you might think..
The length of the bullet is a matter of its composition, its specific gravity, its ogive, either tangent or secant. A secant ogive is generally longer and usually has a boat tail. In general a longer bullet will have its center of gravity and the center of presure further apart than a shorter bullet this alone will affect the rotational stability and need to be taken into consideration when calculating the proper twist.
Over-stabilization will have a degenerate influence on accuracy at long range. So, too much twist is not too good either it will make a bullet fly with its nose up rather then follow the trajectory hence it looses airo dynamic efficiency.
There are some good programs on the net for calculating twist. The Greenhill formula is not one of them.
The Berger bullet catalog lists all their bullets with recommended twists, taking into consideration prevailing velocities that these bullets will be shot at and is an excelent guide.
Some of the new bullets with multy density metals , like40% copper, 55% lead and alloy or plastic tips can get very long and need lots of speed or a fast twits. The metal distribution can have detrimental effects on bullet stability.
For a hunting bullet a flat base tangent ogive IMHO is best suited for most applications and are less twist senitive out to sensible ranges of abot 350
yrds.
Mitchell, yes I did understand what you meant. I put my post in just as food for thought. It is possible it could be done. Once you barrel is shot out you can have it rebored but a new Handi barrel is more cost efective.
