4 vs 5 vs 6 groove barrels

Ruger007

Ruger007

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Probably a Ford vs Chevy vs Chrysler thing. But,. I have been doing a bunch of custom barrels for myself lately. Can't travel might as well build nice rifles.

I keep asking myself this question. There seems to be the options of the 4 or 6 groove and the 5, 5r groove. Plus gain twist.

Any real difference in the end? Or a gimmick?

Thanks
 
Also interested to know here.
So far my 4x IBI centerfire barrels have all been in 5R.
Without actually having a real reason to do so, it is rumoured to clean easier than other groove patterns.
 
I believe the theory behind gain twist is that starting at a slower twist first means more of the force behind the bullet is being used to accelerate it in a straight line and less of the force is being diverted away by the rifling into rotating the bullet. This is supposed to mean that the bullet will be further down the barrel after a certain amount of time compared to a barrel with a uniform twist, supposedly reducing peak pressure. That being said, most bigger military cannons are using gain twist, so maybe there is something there...
 
Lilga makes 3 groove barrels. I have a friend that swears that you need an odd number of grooves for accuracy so the grooves are not 90 degrees to each other. I have always shot 4 groove barrels for long range and never really see a reason to change. That being said, if push came to shove and I needed a barrel right away I would take a 4, 5 or 6 groove barrel that I could get right away. I guess for me, it comes down to how long I am willing to wait for a barrel.
 
I own a few of Ron Smith's gain twist barrels. They do work. Seem to allow slightly higher velocities with no increase in pressure signs. As for the number of grooves, I've seen barrels that were accurate with everything from 2 to 5, so far. I honestly don't see much of a difference. In black powder it might help with fouling. - dan
 
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5R reduces projectile deformation as it passes through the bore during the firing sequence. By placing the lands opposite of the grooves, the bullets are no longer squeezed on opposite sides ensuring the projectile stays uniform instead of squeezing material into the grooves.


 
One more I know of in production still to add: Lothar Walther polygonal rifling. It has been said that these will have a slight reduction in accuracy... I do not have a Walther barrel with which to compare, but that is what I was told by the gunsmith who installs them.

It is my understanding that the Walther barrels foul less: 5R can be described as a step between these and standard rifling on the issue of fouling.

Dedicated and experienced BR shooters would be the most knowledgeable on the subjects of which are most accurate and foul less... though fouling would have a lot to do with quality of the rifling as well. I have traditional and 5R barrels... they all get copper fouled and no matter what need cleaning. They also shoot to my accuracy requirements so while that is the extent of my concern I am still interested in knowing what's what and if my conclusions are 100% correct rather than just hypothesis.
 
In my distant memory there is the trace of a discussion with barrel maker regarding the optimum surface area of lands vs grooves ... that being a ratio of 2/3 to 1/3 ?
 
I've run 3, 4 and 5 groove barrels... they all shot tiny groups. Can't say that one is better or even provides a noticeable difference.
 
Largely a fad thing. Lester Bruno (US Benchrest shooter and founder of Bruno Shooting Supplies) did a fair amount of research into gain twists for the 6PPC and it was determined that a very very slight amount of gain on the twist produced good results. As to 4 vs 6 grooves, I see it as the fewer places for carbon to build up the better, but no difference to results. 5R theorized that radiused rifling allowed better obturation of the bullet in the bore, and non-opposing lands deformed bullets less, but it is a largely theoretical thing. Like most things in shooting, you will get conflicting anecdotes. I think it is better to simply get a barrel from a good maker, and use what they make.
 
Bartlein, a leading manufacturer, specifies grooves according to calibre, i.e: .30 - 4/5R, .338 - 5R/6, .50 - 7/8, 20mm - 8/9/15.

Further, we have not seen other than 4 groove used by BR shooters - at least the great majority who use Krieger and Bartlein in 6mm .
 
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