What is so special about 5R rifling?

A few things that are different about 5r:
As the name suggests, there are 5 grooves instead of an even number. This is believed to help seal the bullet in the bore better because no grooves are directly opposite another. This is also less stressful on light jackets, like match bullets usually have.
The angle and shape of the grooves and lands is also different and many say it is easier to clean as well as also being less stressful to jackets because the angle of the sides of the lands is more extreme.
Imagine more of a "v" profile instead of an almost square groove

Yep, 5 groove with slanted land edges. The slanted edges are said to reduce fouling by not cutting as aggressively into the jacket, and the less sharp edges allow better gas sealing and reduced friction. Sort of a halfway point between traditional cut rifling and polygonal rifling.

I've only messed with one rifle with 5R rifling so far, and it seems to run pretty fast and clean easily. Pretty decent accuracy, too.

Isn't this more common outside of North America?

N555 said:

Isn't this more common outside of North America?

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I know polygonal rifling generally is, but I don't know about 5R.

Less damage and distortion to bullets, lower drag.

4 Groove, 6 groove, 5R, 3P, it can all shoot small. 5R is just nice to bullets.

I've seen 5r rifling mentioned for a few years and always wondered what it was.

Thanks

An American Rifleman article said that 5 R stands for 5 grooves, Russian pattern.
That it was developed by barrel maker Boots Obermeyer after he got a look at an AK 74 which has the tapered lands but only 4 grooves.

They all could have just gone back to some turn of the century British rifles where it was known as "trough shaped rifling."


Enfield rifling has 5 square grooves. Ken Waters' .30-06 BSA did well with cast bullets, he thought because of the opposite lands and grooves.

A lot of period muzzleloaders have an odd number of grooves. The advantage there was a land opposite the rifling cutter to support it as the mostly wooden tooling worked.

Supposedly, less "pinch" on the bullet's jacket. Only one "pinch" point at one end, none on the opposing end as you would typically find on "conventional" rifling.

N555 said:

Isn't this more common outside of North America?

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Fairly common nowadays, if you're frequently looking into these kinds of things.

"I want a Bartlein 5R finished up by Dave Tooley," one would frequently hear.

Driftertank said:

I know polygonal rifling generally is, but I don't know about 5R.

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I'd like to see high quality polygonally - rifled barrels available locally - but I'm under the impression that cutting is less machinery - intensive compared to using these giant hammers.

Is Lothar Walther USA local enough?
They list polygonal barrels but don't say how they are made; and hammer forged barrels but don't say how they are rifled.

https://www.lothar-walther.com/gun-barrel-blanks/hammer-forged-gun-barrels/?p=1

The only thing that matters is what a particular shooter can do with what is in his/her hand. My $400 Ruger American with Federal nontypical soft points shoots as well as my 5R rifled Remington custom shop refurbished M24 with M118 when I am on the trigger.

No Love out there for the 2-groove barrel ?
I have a 1903-A3 Springfield that does quite well with the right cast bullet ...(Lyman 311334)
It has to fill the bore and be sized correctly ... but it's a Doozy when done right .
Gary

War time barrels may shoot well, my two groove Lee Enfield



shoots cast bullets more accurately than my five groove Lee Enfield.



I don't have a pristine M1917 to prove anything about 5 groove barrels



There was a pre WW1 period where shooters with Krag's were using cast bullets, but pretty much after that, cast bullets were replaced with jacketed. Military rifles were not made to be target rifles, and war time production barrels, two groove, four groove, and five groove, were made under "get it out the door" conditions. If it went bang, that was good enough in a war where 60,000 men a mouth were being removed from the battlefield, and the replacements needed thunder sticks. It was worse for the Russians, there were times at Stalingrad were the average expected lifetime of a Russian solider was 24 hours.

Almost all the discussion about barrels ignore the intrinsic accuracy of bullets. The assumption is that bullets are all perfect and that the different barrel types are the difference on target. I do not believe this at all, and I am going to claim this is the reason for all the differing opinions. Bullets are a confounding factor. They are not all of the same weight, the jackets vary in thickness, and the distribution of lead cores vary enough that the center of gravity varies between bullets of the same lot. All of the variables create inaccuracy. I can say, different bullets shoot wildly different, in the same tube. Therefore I don't know of any reasonable test that can be funded on a hobbyists income, to prove that one rifling configuration is inherently better than any other.

All we as shooters can do is buy barrels by reputation. You can talk to the barrel makers, ask the right questions about surface finish, bore dimensions, bore concentricity, and decide for yourself if you want the tube. One barrel maker told me barrel making techniques have a learning curve, and the different techniques, be they cut rifling, button rifling, broach rifling, all have their unique problems, but once mastered, a good barrel can be made from any. And don't forget a chambering is important, a bad chambering job with an oval chamber will not give best accuracy no matter how good the blank. And another issue, the firing pin should be hitting the center of the primer, off set firing pin hits create inconsistent ignition, and no matter how good the blank, if ignition is not consistent, accuracy will not be either.

I am getting to be of the opinion that a barrel choke is a good thing. I have a Benchmark 22lr where the maker deliberately created a choke, and of all things, I have a 1937 M70 that clearly has a choke at the muzzle. The patch tightens up as it approaches the muzzle. Both of these barrels are exceptionally accurate. There might be something to tight barrels being more accurate, all things being equal.

I’ve used 2, 3, 4, 5, 6, 12, and 16 groove barrels with conventional, poly, ratchet, and 5R rifling. Hammer forged, pull button, push button, cut rifled too. Conventional 4, 6, and 5R rifling have been the most accurate barrels I have owned. Poly is fast, in every one of them I have owned. Not enough to be a driving force to exclusively buy them, but fast.

Slamfire said:

Almost all the discussion about barrels ignore the intrinsic accuracy of bullets. The assumption is that bullets are all perfect and that the different barrel types are the difference on target. I do not believe this at all, and I am going to claim this is the reason for all the differing opinions. Bullets are a confounding factor.

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In a rare excursion into rifled barrels by shotgunner Don Zutz, he said a prewar Model 70 was as accurate as a new rifle, given fresh bullets. This back in the 20th century, likely barrels and bedding are better now.

Jim Watson said:

In a rare excursion into rifled barrels by shotgunner Don Zutz, he said a prewar Model 70 was as accurate as a new rifle, given fresh bullets. This back in the 20th century, likely barrels and bedding are better now.

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I bedded my 1937 and 1940 M70's and free floated the barrels. Both shoot exceptionally well for hunting rifles. What really hurt their accuracy was the peculiar bedding ideas of the period. That is the old timers wanted to tie the barrel down, pre 64's have a barrel band which holds the barrel in the stock. I consider this horrible. Maybe this worked for black powder rifles, it surely does not for smokeless.

this rifle was made in 1941 and had been shot very little.





this is in the barrel channel



this is a 1941 Remington M37 22lr target rifle. Due to its 3.5 lb trigger and M1903 stock this rifle is hard to shoot consistently. These characteristics come from the NRA rules of the period, and those rules were written by Army rules committee members who wanted civilians to be shooting rifles which were as close as possible to military rifles, hence the 3.0 to 3.5 trigger pull requirements, which came from the M1903. The stock is close to the M1903 pistol grip. That being said, with all its issues I was able to shoot this at a two day Regional, and shot these groups in the 100 yard match

This should be a 400-32, which happened to be the high 100 yard match score.



When I look at vintage books, and the targets they present, I believe vintage rifles probably did have good barrels. Their bedding was usually bad, and that would account for the rather large groups I see in these books. But mostly, I believe the large groups were due to period bullets. They could cut good barrels, chamber them properly, and make inherent accurate rifles. They could not make inherently accurate bullets.

I don't have any period bullets to prove this one way or another, just happen to have a few vintage rifles with excellent barrels. The ones with shot out barrels, such as the M1917 above, it blows chunks. If I had been through two World Wars, I would be worn out too.

The Glockodile said:

I'd like to see high quality polygonally - rifled barrels available locally

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I used Jim’s link and spec’ed a Savage 12 26” featherweight polygon rifled barrel in a seven twist and fluted for $783.67. It said six grooves, so it’s a hexagon I fathom. I won’t know for sure, that’s too much for me.

In their custom barrel section there is a menu for choosing everything they offer. Of course, some of there options can’t be done with polygon rifling, but many can.

I am a fan of the 5R. It seemed to be an option for any AR barrel I’ve bought, so I chose it.
I don’t know if I spend less time cleaning my rifles than my associates because of the rifling, my favorite surfaces treatments(Nitride), or I just don’t spend as much time cleaning.

4v50 Gary said:

We copied it from the Russians. For once they may legitimately claim credit for inventing something.

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Let’s not get too crazy. I hear they just broke a cutting button and forced it into a smaller bore to use it anyway. The missing groove and rifling shape is just the “happy coincidence” result.

4v50 Gary said:

We copied it from the Russians. For once they may legitimately claim credit for inventing something.

Click to expand...

To quote a usually reliable source (Me!)

Jim Watson said:

They all could have just gone back to some turn of the century British rifles where it was known as "trough shaped rifling."

Click to expand...

But I concede that what Boots Obermeyer was looking at was Soviet.

4v50 Gary said:

We copied it from the Russians. For once they may legitimately claim credit for inventing something.

Click to expand...

Good poets borrow, great poets steal!

I never had more than a few original ideas, and have come to the conclusion it is far better to use the good ideas of others, than to re invent the wheel.

Only mad men are original, and their ideas don't work.

Slamfire said:

War time barrels may shoot well, my two groove Lee Enfield

View attachment 1104860

shoots cast bullets more accurately than my five groove Lee Enfield.

View attachment 1104861

I don't have a pristine M1917 to prove anything about 5 groove barrels

View attachment 1104862

There was a pre WW1 period where shooters with Krag's were using cast bullets, but pretty much after that, cast bullets were replaced with jacketed. Military rifles were not made to be target rifles, and war time production barrels, two groove, four groove, and five groove, were made under "get it out the door" conditions. If it went bang, that was good enough in a war where 60,000 men a mouth were being removed from the battlefield, and the replacements needed thunder sticks. It was worse for the Russians, there were times at Stalingrad were the average expected lifetime of a Russian solider was 24 hours.

Almost all the discussion about barrels ignore the intrinsic accuracy of bullets. The assumption is that bullets are all perfect and that the different barrel types are the difference on target. I do not believe this at all, and I am going to claim this is the reason for all the differing opinions. Bullets are a confounding factor. They are not all of the same weight, the jackets vary in thickness, and the distribution of lead cores vary enough that the center of gravity varies between bullets of the same lot. All of the variables create inaccuracy. I can say, different bullets shoot wildly different, in the same tube. Therefore I don't know of any reasonable test that can be funded on a hobbyists income, to prove that one rifling configuration is inherently better than any other.

All we as shooters can do is buy barrels by reputation. You can talk to the barrel makers, ask the right questions about surface finish, bore dimensions, bore concentricity, and decide for yourself if you want the tube. One barrel maker told me barrel making techniques have a learning curve, and the different techniques, be they cut rifling, button rifling, broach rifling, all have their unique problems, but once mastered, a good barrel can be made from any. And don't forget a chambering is important, a bad chambering job with an oval chamber will not give best accuracy no matter how good the blank. And another issue, the firing pin should be hitting the center of the primer, off set firing pin hits create inconsistent ignition, and no matter how good the blank, if ignition is not consistent, accuracy will not be either.

I am getting to be of the opinion that a barrel choke is a good thing. I have a Benchmark 22lr where the maker deliberately created a choke, and of all things, I have a 1937 M70 that clearly has a choke at the muzzle. The patch tightens up as it approaches the muzzle. Both of these barrels are exceptionally accurate. There might be something to tight barrels being more accurate, all things being equal.

Click to expand...

I read a couple of years ago Steyr when hammer forging a barrel did the chamber and barrel in one shot resulting in perfect alignment

Cool name. Any better than any other rifling? I wouldn’t count on it.

Who made it matters more than the geometry, in my opinion