The twists given are standard, but the button could be made with any twist. You will find there are far
more accurate combinations than the factory twist, but they are a good starting point.
TWIST FORMULA
The formula for finding the correct angle for the twist that you want for the rifling button is the diameter of
the groove, which is .308 (30 Caliber); 308 x pie is 96761054, this answer divided by the twist gives you
an answer of .080634.
Now look at a sine chart and find that figure, it will be 4 degrees and 37 minutes. That is the angle that
you want to cut the grooves on the button to get a 1 in 12 twist.
In a 17 caliber for example you will find that the 1 in 10 twist is fairly well standard. I have done quite a bit
of experimenting and have found that a 1 in 14 twist for me has been very accurate. It has given me
consistently 1/2 minute or under groups at 100 yards. The main trouble in accuracy in 17 calibers
seems to be the bullets.
I have found that the slightest air pocket in the bullet had a tendency to throw the bullet off in the 1-14
twist. With good bullets, the 1-14 will be found superior for top accuracy.
The 1-10 twist will usually shoot the poor made bullets better with considerable accuracy on the
average. This is also true of the other calibers. Take the 30 calibers for example. The 150-grain bullet
will shoot like a house afire with the 1-14 twist.
One of my most accurate and favorite game rifle was a 243 with a 1-14 twist. The rifle was used for long
range on coyotes, crow, etc. I used a 75-grain bullet for the best accuracy.
If you want to experiment, you will probably come up with a far more accurate rifle by doing this. You can
tailor your rifle to shoot the bullets and speed that you want. The main problem you may have is with
bore tolerance. This will be with the steel that you use. Every barrel maker is plagued with this problem.
If you have hard spots in the barrel, you will come out with tight spots in the barrel, and if there are soft
spots, there will be loose spots. I have got such bad steel that when the barrel push it a short ways, and
then it would drop 8 to 10 inches before stopping. What you had is a junk barrel.