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I am looking for a new hunting rifle, and one of the features I keep seeing advertised is 5R rifling where there are 5 lands and grooves instead of 4 or 6.

Supposedly this makes the barrel more accurate because the lands oppose a groove instead of each other thus deforming the bullet less.

I have yet to see any solid evidence to back this up one way or another, and some say that the difference is marginal if at all.

Is there any good evidence or tests that 5R rifling is better than the traditional 4 or 6 land rifling?

  • Where to ask about firearms? I suggest you take it to Engineering – Jan Doggen Nov 5 '18 at 13:35
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    @JanDoggen Hunting is on topic outdoors.meta.stackexchange.com/questions/42/… and that would include the tools and gears for that. – Reinstate Monica Nov 5 '18 at 15:52
  • I am certain--but lack the references to prove it, so won't make an answer--that of the many variables affecting accuracy in hunting, the barrel is the least of them (providing a good quality barrel, however many grooves it has). Sub-moa groups are not done without a sling in field positions, right? So your position, stability, trigger control, breathing, all of that is where accuracy happens (or doesn't) when hunting. I claim that--again, given a decent barrel--the barrel is not the big contributor to hunting accuracy. – Wayne Conrad Jun 14 at 20:02
  • @WayneConrad If the gun is considered independent of the shooter, the barrel is probably one of the more important parts – Reinstate Monica Jun 15 at 1:24
  • @CharlieBrumbaugh I think that's true, and why you see bench shooters pay so much attention to the barrel. Hunting is a long way from shooting from a rest. My claim is that, as long as the barrel is at all decent, other factors dominate accuracy in hunting. I wish I had data to support my claim. – Wayne Conrad Jun 15 at 20:02
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tl;dr: No. Any theoretical advantage of one rifling profile over another is lost in execution.

Since this is a question of practice, not theory, I appeal here to the experience of authorities in this space.

Bartlein Barrels, which for years has been on the forefront of barrel research and manufacturing, and whose barrels are the most widely used in competitive precision shooting, has several comments on 5R rifling versus more conventional rifling (i.e., even numbers of grooves with square shoulders):

Which is better 5R style rifling or conventional rifling? In terms of accuracy and barrel life we don’t see a difference. There are a lot of varying opinions on this. Some say if you want hard core accuracy to go with conventional rifling. We feel in the real world there is no real difference. The more uniform your bore and groove sizes over the entire length of the barrel, the more uniform the twist and the straighter the blank the more forgiving the barrel is going to be.

Some say the 5R style rifled barrels clean easier? Maybe from a carbon fouling stand point because your patch isn’t trying to get down into a 90 degree corner vs. conventional rifling. The way we clean our barrels we don’t see a difference. From a copper fouling stand point we see no difference here.

Bartlein does concede the possible theoretical advantage of 5R rifling in the way it engraves the bullets, but they have not seen evidence of that in practice. (And if they did, they would be among the first to advertise it.)

Among the factors that affect accuracy more than rifling profile:

  • Precision and uniformity of the bore. This is affected by every step of manufacturing and rifling the barrel blank, from drilling the bore to rifling it to finish lapping and stress relieving.
  • Finish and fit of the barrel. On the breech end a perfect barrel can be ruined if the chamber and leede are not cut precisely and squarely to the bore. On the muzzle end minuscule defects in the crown can markedly reduce accuracy.

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