5R rifling

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Big G

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I was reading up on a Remington 700ss military spec .308 & it was stating it had 5R M24 type rifling. Can anyone explain to me what type of rifling that is? Thank you.
 
I'll take a stab at it.

5R rifling contains 5 lands and grooves and the lands have a sloping rather than straight wall. They are supposed to foul less. Boots Obermeyer made them famous in the US, but they are offered by several makers today. James
 
I figured it was 5 riflings but I wasn't sure about the style. From what I have been reading it is a very accurate rifling. Thank you for your input.
 
I have a Shilen 4C barrel. That is 4 lands and grooves, with the lands canted on one side. Can't say it shoots any better or worse than the other Shilens I have. I do believe it may clean a bit easier than the others. JMO

Donald
 
JD Mock said:
5R rifling contains 5 lands and grooves and the lands have a sloping rather than straight wall. They are supposed to foul less. Boots Obermeyer made them famous in the US, but they are offered by several makers today. James
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Foul less and tear the bullets up less for long distance shooting. Milspec rifle is supposed to be a real nice shooter.
 
5 groove rifling will supposedly shoot FMJ bullets better than a 4 or 6 groove barrel. This is because there are no opposing lands so the bullet is squeezed less. With an open based FMJ bullet such as M80 ball or the old M118 special ball, lead squeazed out of the base will affect the accuracy. The OTM bullets like M852 and M118LR have space in the nose of the jacket for the lead to squeaze into without affecting the bullet profile. Since the M24 and the M110 are designed to shoot all military ball ammo, the 5R was used to get the best results. The British used odd number grooves in there rifles for the same reason, as far back as the .577 enfield musket.
 
How many of those "good" barrels will shoot a military open based full metal jacket bullet? Having built and shot military match and sniper rifles for over 25 years, and currently working on the M24E1 program, I have seen alot of different barrels shot under conditions most shooter wouldnt take their rifles out of the case let alone out of the car. Unlike civilian rifles, Military sniper rifles are built to shoot a small range of ammo under varying conditions. We test at -65F to +165F, with sand mud and ice thrown in. I have soft caught bullets to see what they look like and have seen the lead squeezed out of the bases. When we were shooting M14NM rifles our barrels for 168gr SMK was a 6 groove 1-12", that air gauged at no more than .3084 groove dia. giving us 1/2 min. groups at 600yrds. The M118 173gr FMJ bullet would not shoot out of these barrels, we found that the 4 groove 1-12", .3087groove barrels would shoot them. This is when we started working on the M24 program with 5R barrels. If you have the ability to pick a bullet that suits your barrel, then pick the correct powder charge, etc., then that is a good barrel.
 
I am not a milgunsmith, but when you have a good barrel, you have a good barrel. The military is finding that Melonite QPQ treatment makes their good barrels last longer. What proof is their that the number of lands and grooves matter? I have shot some very good 5R and 4 groove ratchets, but I have shot just as many of the conventional rifling that shot and lasted as well.
I think you will find your barrelmaker makes more difference than the land and groove configuration.
Butch
 
Butch Lambert said:
I am not a milgunsmith, but when you have a good barrel, you have a good barrel. The military is finding that Melonite QPQ treatment makes their good barrels last longer. What proof is their that the number of lands and grooves matter? I have shot some very good 5R and 4 groove ratchets, but I have shot just as many of the conventional rifling that shot and lasted as well.
I think you will find your barrelmaker makes more difference than the land and groove configuration.
Butch
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Theres a lot to be said for workmanship and metalurgy, and the bore suited to the bullet type, but experiments going back to the 1840's strongly suggest that, workmanship etc being equal, an uneven number of grooves in general gave best accuracy. That and multiples of three, with six groove giving equal or superior results to a five groove.
I once owned a copy of "Bosworth on the Rifle" first printed in the 1840's, I believe he detailed this sort of experiment in that book.
I may still have the book, I just haven't seen it around here in years.

Last I heard the 5R rifling pattern was more geared towards reducing effects of gas erosion, coupled with Martensitic Stainless steel barrels.

The Sniper Rifles may be a sort of semi-custom proposition but the barrels are still a mass produced item. Sometimes features of a rifle are chosen for consistent results and ease of manufacture to acceptable tolerances than anything else.
 
Kevin Thanks for sharing your knowledge with us.

We all learn something new every day. Learning about 5R rifling is much better that listening to the daily news and learning about American Socialism.

I have been shooting several variations of 5R rifling with good results.

I think it has some advantages over other straight wall rifling.

I cann't comment on the even number rifling issues.

Nat Lambeth
 
The R5 rifling has 115 degree angle between the lands and grooves instead of the standard 90 degree angle. This supposedly reduces the friction and fouling. I have a Remington 700 R5 Special in .308. I get 100fps. higher velocity with a 168gr. Sierra MK in this barrel than another standard barrel. I know that there can be that much difference between two identical barrels, but this is the only comparison I can make. I get excellent accuracy with this barrel- it has a 11 1/4" twist.
 
Supposedly a less abrupt angle at the botton corner of the groove allows the jacket to conform with less gas leakage.
I've heard of grooves being cut with a radius at the corners for better sealing of the jacket to bore.
I had thought this was how the R5 was cut, but apparently not.
 
Old Gunner, I believe you are correct- I think the 5R rifling has radius corners with a 110-115 degree angle between lands and grooves.
 
jkgeary said:
Old Gunner, I believe you are correct- I think the 5R rifling has radius corners with a 110-115 degree angle between lands and grooves.
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Thats good. Radiused corner grooves were a feature of the rifling pattern used by Harry Pope, in that case for best sealing of the lead bullet seated from the muzzle but propelled by a blank charge.

Very slight rounding of the edge of lands by normal wear can increase accuracy, one reason why US military .30 barrels are said to steadily improve in accuracy for the first 3500 rnds fired.
 
Butch Lambert said:
Where can we read about this?
Butch
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If you mean the various rifing patterns I may be able to find links to free downloads of books on the subject printed when these rifling styles were being developed.
The Internet Archive and Google Books have many public domain books on firearms available for downloading, many by famous firearms authorities like Hatcher, Whelen, Kephardt, Lord Cottesloe, WW Greener, etc.
 
I've read some of what you gave as reference and actually have a piece of a barrel of about 2" inside diameter made that way. I'm looking for the tests that show the barrels get more accurate after 3500 rounds.
Butch
 
Butch Lambert said:
I've read some of what you gave as reference and actually have a piece of a barrel of about 2" inside diameter made that way. I'm looking for the tests that show the barrels get more accurate after 3500 rounds.
Butch
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A great big AMEN to that!

Donald
 
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