Selecting the Right Barrel
When it comes to selecting the right barrel for your rifle, there are many factors that need to be taken into consideration to ensure that you have the best barrel for your rifle/bullet combination. We will discuss the following: Length, Twist Rate, and Contour
Length
The overall length of your barrel is going to primarily contribute to the muzzle velocity of your rifle and is not indicative of precision. A short barrel is not going to be less precise than a longer barrel simply because of its length, and theoretically, all else being equal, a shorter barrel will be stiffer and thus prone to more consistency.
On average, a barrel will gain/lose 25 feet per second (FPS) in velocity for every inch of barrel length. Therefore you can expect a 28" barrel to shoot approx. 100 FPS faster than a 24" barrel. When researching a cartridge for a rifle build, know that most ammunition companies use 24" test barrels unless otherwise stated. While the extra velocity can look inviting it does come with added weight to the rifle (approx 2.5 oz per 2" for Proof Research carbon fiber barrels) and overall length which can be cumbersome in certain scenarios.
Lastly, realize that if you go with a short barrel you are going to see lower velocities, but if you are looking to get a 6.5 mm bullet to go 2700 FPS out of a 16.5" barrel then realize that you will need a 6.5 PRC cartridge behind it to do so. You will not be maximizing the potential of the catridge but you will be assembling a purpose built rifle.
Twist Rate
This is probably the most common question and the least understood subject when it comes to selecting a barrel. The twist rate refers to the rifling that is cut into the barrel and determines how many inches it takes the bullet to complete one rotation. For example, a 1:10 twist means that the bullet makes one full rotation in 10". This means that a 1:9 twist is a faster twist than a 1:10 because the bullet is making the same one turn in less distance.
Without getting too deep into the weeds, the heavier your bullet is the faster your twist rate needs to be. For example, if you are shooting a 180 gr 30 caliber bullet, a 1:10 twist will work just fine, but if you decided that you wanted to shoot a 245 gr 30 caliber bullet, a 1:10 would be insufficient to properly stabilize the bullet. The easiest way to find out which twist rate is appropriate for your caliber/catridge is by using the Miller's Stability formula which can be found here. Many companies are now putting the minimum twist rate on their ammunition and bullet boxes.
Here is a list of common twist rates per caliber:
.224 - 1:7 | 1:8
.243 - 1:7 | 1:7.5 | 1:8
.257 - 1:7.5 | 1:10
.264 - 1:7.5 | 1:8
.277 - 1:7.5 | 1:8.4 | 1:10
.284 - 1:8 | 1:8.4 | 1:9
.30 - 1:8 | 1:9 | 1:10
.338 - 1:9.4
.375 - 1:12
Contour
Lastly, you need to consider the contour which references the overall shape of the barrel and influences the overall weight and stiffness as well. When using a Proof Research carbon fiber barrel blank you will have the choice between the Sendero Light, Sendero, and Bull. The bull barrel is a straight contour, meaning that it does not change at all. It starts at 1.2" at the breech and remains the same size through the entire length of the barrel. The Bull contour is limited in its production by Proof as is generally used for looks as there is no percieved perfomance benifit. The most common contours are the Sendero and Sendero Light. If the lengths are equal, the Sendro weighs approx. 2.5 oz more than the Sendero Light. The Sendero barrel is stiffer and thus lends to better precision overall. I will always suggest that a customer choose a Sendero unless:
A) they are restricted by barrel channel in their current stock
B) they are shooting a non-magnum cartidge
C) they are choosing a barrel under 22"
D) they want the lightest possible rifle and every ounce matters.
If you are replacing a stock barrel on a factory rifle, you need to consider that the Proof contours for their carbon fiber barrels can be significantly bigger than the ones that you are replacing. This typically means that the stock would need to be replaced at the same time. If the contour you are replacing is only slightly smaller it is possible to open up the barrel channel which can be done by you or a gunsmith.
Conclusion
Determine the overall purpose of the rifle and make sure you know what bullet you will be shooting. If you are replacing a barrel, make sure the stock will fit or can be fitted to the Proof contour. If you are building a rifle, then make sure the stock you will be getting is inletted for your selected contour. If you still have any questions, please dont hesitate to reach out to us by clicking here.