Why is the Rifling on a Barrel Important?
What style rifling should I get?
We offer three different types of rifling. 4-groove, 5R, Conventional-5. The style or number of grooves has no real bearing on accuracy and or barrel life. We are able to confidently say this after receiving feedback from ammunition and bullet manufactures using actual test barrels.
Additional benefits of 5R rifling
The 5R style of rifling helps fight bullet failure. This is because of the gentler angle on the sides of the lands vs. conventional style of rifling. Conventional/standard type rifling the land basically meets the groove at a 90 degree corner. So a hard edge. Also with the 5R you have 5 lands in the bore of the barrel. The odd number of lands doesn't directly oppose one another. The combination of these two things deforms the bullet less (less distortion to the bullet jacket) when the bullet makes the jump from the case into the rifling. This helps fight bullet failure.
We have learned that the 5R rifling actually helps the flight of the bullet. This came from an ammunition/bullet maker in late 2019.
A couple exceptions...
With one exception to the comment that is in bold letters above…..the short jacket 6mm bullets (typically in 65-68gr bullets) that the short range bench shooters use. Those bullets don’t like the 5R style of rifling. The best the gun will shoot is in the upper .2xx’s to a flat .3xx group size. It’s usually worse if it’s a boat tail bullet in these bullets as well. Why? The short bearing surface of these bullets in conjunction with the “R” style of rifling…the rifling does the driving and the short jacket bearing surface area on these bullets we feel the rifling doesn’t bite the bullet good enough.