This might help mate
Cheers Paul
Calibers and Twist Rates
Below is a listing of all the calibers and twist rates that we are currently offering. Some twists are available in more than one groove configuration as indicated.
Caliber
Twist
.172 (.17) 6(e),7(e), 9(e), 10(e)
4.6 mm 6(e)
.204 (.20) 9(h), 12(h)
.22 RF 9(h),15,16(a,b),17(e)
.224 (.22) 7(a), 8(a,b), 9, 10, 12(a), 14(a), 15(a)
.234 10
.243 (6mm) 7(h), 8(h), 9(a), 10(a), 12(a), 13(a), 14(a), 15(a), 16
.257 (.25) 7(h), 10(a), 12, 13, 14
.264 (6.5mm) 8(a), 9, 10, 12
.277 (.270) 8(h),10(a, b), 12
6.8 mm 10(a)
.284 (7mm) 7(h), 8(h), 9(a,b), 10, 12, 14
7.5 mm (.305) 11(e)
.308 (.30) 8, 9(a), 10(a,b), 11(a), 12(a,b), 13(a,d), 14(b), 15(a), 16,17(h)
.311 (.3105) 10 (e)
.323 (8 mm) 10
.338 7, 10, 12
.358 (.35) 10, 12, 16
9.3mm (.366) 12
.375 10, 12
.408 (.40) 13, 16
.416 12(c), 13, 14(c)
.423 (.404 Jeffery) 14
.425 W-R (.435) 16
.458 (.45) 14(c), 48(g)
.510 (.50) 15(f), 26, 32(g), 48(g)
All barrels above are 6 groove only EXCEPT as indicated by a letter suffix: (a) also 3 groove; (b) also 4 groove; (c) 8 groove only; (d) also 8 groove; (e) 4 groove only; (f) also 7 groove; (g) black powder twist,and (h) 3 gooove only.
Long Barrels
Our standard length barrels are furnished as a 28" long blank that will finish up to 27". Most barrels can be ordered in a finish length up to 30". Only the following caliber/twist combinations can be ordered over 30" in length. Maximum finish length is 45" unless indicated otherwise.
Caliber ********** Twist** *Grooves
6.5******* ********** 8”******* * 3
7mm**** ********** 7”******* * 3
*********** *********** *9”****** * 4
.308**** *********** 10”***** * 3,6
******* *************** 11”***** * 3
******* *************** 13”***** * 3*(up to 34” and .299" bore dia. for Palma shooters)
.338**** *********** 10”***** * 6
.358 *************** 12” **** **6
.375**** *********** 10”***** * 6
.408**** *********** 13”***** * 6
.416**** *********** 12”***** * 8
******* *************** 13”***** * 6
.435**** *********** 16”***** * 6
.510**** *********** 15”***** * 6
Twist Selection
For help in selecting the correct twist rate for the bullet you plan to use please refer to the chart below. The rate should be based on the heaviest bullet you intend to use. We are also very willing to help you determine the correct twist. You may contact Dan with questions by e-mail CLICK HERE.
BULLET WEIGHT / CALIBER / TWIST RATE CHART
Grain/Cal .172 .204 .224 .243 .257 .264 .277 .284 .308 .338 .358
17-20 9-10 * * * * * * * * * *
25 10 * * * * * * * * * *
30 9 12 * * * * * * * * *
33 * 12 * * * * * * * * *
35 * 12 * * * * * * * * *
37 VLD 6 * * * * * * * * * *
40 * 12 * * * * * * * * *
50-52 * 9 14 * * * * * * * *
55 * * 12 * * * * * * * *
60 * * 12 * * * * * * * *
68-69 * * 9,10 13,14 * * * * * * *
75 * * 9 * 14 * * * * * *
80 * * 8 * * * * * * * *
85 * * 7 12 12 12 * * * * *
90 * * 7 10 * * * * * * *
100 * * * 10 10 * 12 14 * * *
105-107 * * * 8 * * * * * * *
120 * * * * 10 10 * 12 15,16 * *
130 * * * * * * 10 * 14 * *
140 * * * * * 9 10 10 * * *
150 * * * * * * * * 14 * *
140-160 * * * * * 8 10 10 12,13 * *
150-168 * * * * * * * 9 11,12,13 * *
150-180 * * * * * * * * 10,11,12 * *
160 * * * * * * * 9 * * *
175 * * * * * * * 9 * * *
180 * * * * * * * * 10,11,12 * *
200 * * * * * * * * 10,11 10,12 12,16
220 * * * * * * * * 10 * *
225 * * * * * * * * * 10,12 12,16
240-250 * * * * * * * * 10 10 12
300 * * * * * * * * * 10 12
The above chart is from our FAQ section. For more information about choosing the correct twist rate Click Here.
To read an article on bullet design and download a free program that calculates twist rate based on specific bullet dimensions Click Here