The who what & where of 5R rifling
- Thread starter Patch700
- Start date
Jet
Gold $$ Contributor
From Obermyer barrels:
"5R is the form of rifling I developed for use in most target barrels and in many sporting barrels. These barrels have 5 grooves, and the lands have angular sides. I have observed that bullet jackets will deform such that they remain closer to the R-form lands than they will to the sharp-edged lands present in conventional-style rifling. This reduces powder fouling at the corner of the
grooves. The angled form of the lands also helps to reduce jacket failures in quick-twist barrels."
I have spent a good bit of time firing M24s with 5R rifling and they do clean relatively easy when firing M118 ammo.
Do they clean easier or foul less than a Krieger, Brux, Bartlien, etc 4 grove? I don't think so. Less than a standard factory Savage or Remingtion, yes.
Good shooting
Jet
"5R is the form of rifling I developed for use in most target barrels and in many sporting barrels. These barrels have 5 grooves, and the lands have angular sides. I have observed that bullet jackets will deform such that they remain closer to the R-form lands than they will to the sharp-edged lands present in conventional-style rifling. This reduces powder fouling at the corner of the
grooves. The angled form of the lands also helps to reduce jacket failures in quick-twist barrels."
I have spent a good bit of time firing M24s with 5R rifling and they do clean relatively easy when firing M118 ammo.
Do they clean easier or foul less than a Krieger, Brux, Bartlien, etc 4 grove? I don't think so. Less than a standard factory Savage or Remingtion, yes.
Good shooting
Jet
Lapua40X
California Hunter Education Instructor
I have a Bartlein 5R barrel on my .284. If you're familiar with the exasperation of trying to get a bore brush to remove the fouling in the corners of the grooves with conventional rifling you will understand when I say the 5R, among its other virtues, is much easier to clean.
The only thing I can tell you about their Long Range performance is that mine shoots reeeel good.
The only thing I can tell you about their Long Range performance is that mine shoots reeeel good.
jonbearman
I live in new york state,how unfortunate !
I have a shilen 5r and it doesn't foul hardly at all.
Shilen does not make a 5R barrel. All of Shilen's "ratchet" barrels are 4 groove.
http://www.shilen.com/calibersAndTwists.html
http://www.shilen.com/calibersAndTwists.html
DHD
Silver $$ Contributor
Patch700 said:
That's a good way of describing it.
I have 5r's, conventional 4 groove, and Shilen ratchet rifled barrels and they all shoot well. I cannot say that the 5r's really clean easier as I don't shoot a lot of rounds without at least pushing some Bore Tech soaked patches down the bore.
There have been threads on other sites where Frank Green (Bartlien) has stated that he has never seen any accuracy improvement going from 4 groove conventional to 5r. I do think he said that there was a slight difference in clean up, but cannot remember exactly.
Alex Wheeler
Site $$ Sponsor
Anyone using one in benchrest?
Well, there is one con that I know of, and that is the propensity of the chambering reamer to ride up the slanted wall of the riflings and chatter when the chamber is cut. I had this on my first 284 5R barrel and researched it until I found Gordy Gritters' post on the subject (in quotes below). Armed with this knowledge, I bought a second barrel and took it to a well known smith with an excellent reputation. In spite of telling him about the problem and how I wished to avoid it in chambering this new barrel, it came out worse than the first one. The smith said it was the fault of the PT&G reamer. Interestingly enough, I have a 6BR with a 5R barrel that does not exhibit this problem, so maybe it is the 284 reamer.
I'm still not sure how the 5 lobed chamber affects accuracy. The second 284 barrel is the one I used a month ago to make my 1 mile prairie dog kill. It is the least accurate of my custom guns because it throws a lot of fliers, but it will have spells where it puts them all in one hole at 200 yards.
Make sure your smith knows about this potential chatter issue and can handle it before you have a 5R barrel chambered. Here is a link to a thread that discusses the issue.
http://benchrest.com/showthread.php?86975-Reamer-chatter
"MIT, I seriously doubt the reamer is the problem here. Measure the OD on the freebore section on the reamer, and if that measures OK the reamer won't be the problem. It may be something else, but you very well might be experiencing something I frequently see to one degree or another, especially in canted land barrels. Go in with your long-reach indicator and see if the free-bore section of the throat is smooth. My guess is it's not, which means you have experienced reamer chatter.
It's amazing how much reamer flex can happen in these chambers, and it's especially prone to do this in canted land barrels (it can do it in conventional land barrels also, but not nearly as readily). It will do it no matter how true you have the bore dialed in, how well-fitted the reamer bushing is in the bore, how carefully you feed the reamer in, or how big and expensive your lathe is. Carbide reamers are much stiffer and won't do it as bad, but most reamers are HSS and they will definitely do it!
I started seeing this unexplained reamer chatter phenomenon as soon as I started using canted land barrels quite a few years ago. I called the barrel maker on it a number of times, but he told me I was the only guy in the country he knew of who had seen this. I told him maybe I was the only guy who consistently measures for this all the way through the chambering process, but I see it to this day on about every canted land barrel I chamber. I still use and like canted land barrels, but I just know to be extra careful when chambering them.
I often demonstrate this in my classes (and will be showing this in-depth in an upcoming "Advanced Chambering" DVD) - I'll tell the students exactly when the chatter will start. I will be chambering along and the indicator shows absolutely no chatter whatsoever anywhere in the chamber. When the reamer is far enough in to start cutting the throat, we will then instantly be able to measure chatter through the whole length of the chamber. In every single case, when I can feel the reamer start to cut the throat, I'll tell them we'll now put the indicator in and see what happens - sure enough, we can now measure chatter beginning, not only in the throat area, but in the entire chamber. Usually its very minor and if you didn’t measure for it you’d never know anything was going on, but it’s there and can get worse if you don’t catch it in time.
Then I show them the method I now use to prevent this as much as possible - simply prebore the lands away clear to the end of the neck while you are pre-drilling and boring the body of the chamber. This allows the reamer to be completely seated (and now fully supported) before it finally gets to the throat area as it comes to full depth. When the reamer is fully supported and cutting completely before it finally picks up the throat way at the end, this really minimizes chatter problems.
Now if you have to cut a longer throat with a separate throating reamer after you've done using the main chambering reamer, you really have to be careful the chatter doesn't get away from you, since the body of the throater is completely unsupported. Both the throater and the chamber reamer will benefit by using the wax-paper wrap trick since this dampens the flex somewhat and will help keep you out of trouble.
I've tried quite a few things over the years trying to figure out what causes this and how to prevent it. In my opinion, what happens is the conventional land barrels have straight vertical sides on the lands, so when the straight vertical flutes on the reamer cuts into them, they meet square and there is no side pressure on the reamer flutes so they cut very nicely. But in canted land barrels, the lands are sloped at a pretty good angle, so the flutes of the reamer want to ride up the lands instead of cutting straight into them. Most of the canted land barrels are an odd number like 5 land/groove, so each time a reamer flute tries to ride up a land, it pushes away from that land making the opposing flutes dig into the grooves between the opposite lands (you can usually see this in a borescope if you know what to look for). Measure it and you'll see that the freebore is now 5-sided and not round!
This can happen severely enough that the effective diameter of the freebore section in the throat (the tops of the chatter) is smaller than the reamer itself. The reamer just flexes up and down in these grooves and flexes sideways just enough to form "lands" which is what you're measuring with your indicator. I've often seen it (and measured it) where the reamer chatter in the throat made the effective freebore smaller than the bullet diameter like you've seen here.
Check it out and see if maybe this is what you're experiencing. Hope this helps!"
I'm still not sure how the 5 lobed chamber affects accuracy. The second 284 barrel is the one I used a month ago to make my 1 mile prairie dog kill. It is the least accurate of my custom guns because it throws a lot of fliers, but it will have spells where it puts them all in one hole at 200 yards.
Make sure your smith knows about this potential chatter issue and can handle it before you have a 5R barrel chambered. Here is a link to a thread that discusses the issue.
http://benchrest.com/showthread.php?86975-Reamer-chatter
"MIT, I seriously doubt the reamer is the problem here. Measure the OD on the freebore section on the reamer, and if that measures OK the reamer won't be the problem. It may be something else, but you very well might be experiencing something I frequently see to one degree or another, especially in canted land barrels. Go in with your long-reach indicator and see if the free-bore section of the throat is smooth. My guess is it's not, which means you have experienced reamer chatter.
It's amazing how much reamer flex can happen in these chambers, and it's especially prone to do this in canted land barrels (it can do it in conventional land barrels also, but not nearly as readily). It will do it no matter how true you have the bore dialed in, how well-fitted the reamer bushing is in the bore, how carefully you feed the reamer in, or how big and expensive your lathe is. Carbide reamers are much stiffer and won't do it as bad, but most reamers are HSS and they will definitely do it!
I started seeing this unexplained reamer chatter phenomenon as soon as I started using canted land barrels quite a few years ago. I called the barrel maker on it a number of times, but he told me I was the only guy in the country he knew of who had seen this. I told him maybe I was the only guy who consistently measures for this all the way through the chambering process, but I see it to this day on about every canted land barrel I chamber. I still use and like canted land barrels, but I just know to be extra careful when chambering them.
I often demonstrate this in my classes (and will be showing this in-depth in an upcoming "Advanced Chambering" DVD) - I'll tell the students exactly when the chatter will start. I will be chambering along and the indicator shows absolutely no chatter whatsoever anywhere in the chamber. When the reamer is far enough in to start cutting the throat, we will then instantly be able to measure chatter through the whole length of the chamber. In every single case, when I can feel the reamer start to cut the throat, I'll tell them we'll now put the indicator in and see what happens - sure enough, we can now measure chatter beginning, not only in the throat area, but in the entire chamber. Usually its very minor and if you didn’t measure for it you’d never know anything was going on, but it’s there and can get worse if you don’t catch it in time.
Then I show them the method I now use to prevent this as much as possible - simply prebore the lands away clear to the end of the neck while you are pre-drilling and boring the body of the chamber. This allows the reamer to be completely seated (and now fully supported) before it finally gets to the throat area as it comes to full depth. When the reamer is fully supported and cutting completely before it finally picks up the throat way at the end, this really minimizes chatter problems.
Now if you have to cut a longer throat with a separate throating reamer after you've done using the main chambering reamer, you really have to be careful the chatter doesn't get away from you, since the body of the throater is completely unsupported. Both the throater and the chamber reamer will benefit by using the wax-paper wrap trick since this dampens the flex somewhat and will help keep you out of trouble.
I've tried quite a few things over the years trying to figure out what causes this and how to prevent it. In my opinion, what happens is the conventional land barrels have straight vertical sides on the lands, so when the straight vertical flutes on the reamer cuts into them, they meet square and there is no side pressure on the reamer flutes so they cut very nicely. But in canted land barrels, the lands are sloped at a pretty good angle, so the flutes of the reamer want to ride up the lands instead of cutting straight into them. Most of the canted land barrels are an odd number like 5 land/groove, so each time a reamer flute tries to ride up a land, it pushes away from that land making the opposing flutes dig into the grooves between the opposite lands (you can usually see this in a borescope if you know what to look for). Measure it and you'll see that the freebore is now 5-sided and not round!
This can happen severely enough that the effective diameter of the freebore section in the throat (the tops of the chatter) is smaller than the reamer itself. The reamer just flexes up and down in these grooves and flexes sideways just enough to form "lands" which is what you're measuring with your indicator. I've often seen it (and measured it) where the reamer chatter in the throat made the effective freebore smaller than the bullet diameter like you've seen here.
Check it out and see if maybe this is what you're experiencing. Hope this helps!"
I have used a number of them and they are winners.
I'm shooting the Bartlein 5R in .30 cal for score.
They are 17 twist and .300/.308 on the lands and grooves.
They don't copper readily and clean easily. Of course, I stay on top of that.
We do our own gunsmith work and have not had a problem in chambering these barrels.
Oh, and yes, fast, I am using it in BR competition.
I know for a fact that others are, as well.
I'm shooting the Bartlein 5R in .30 cal for score.
They are 17 twist and .300/.308 on the lands and grooves.
They don't copper readily and clean easily. Of course, I stay on top of that.
We do our own gunsmith work and have not had a problem in chambering these barrels.
Oh, and yes, fast, I am using it in BR competition.
I know for a fact that others are, as well.
butchlambert
Site $$ Sponsor
lrgoodger,
Guess that I am lucky. Never had that problem. Maybe I chamber different than you. I have found no advantage to the canted land barrels.
Guess that I am lucky. Never had that problem. Maybe I chamber different than you. I have found no advantage to the canted land barrels.
I don't chamber my own barrels, but both of the problem barrels were done with the same reamer, so maybe the last smith was right. Maybe it is just a bad reamer. But when I found that the chatter made five lobes in the chamber that corresponded to the lands, I investigated and found Gordy's write up (actually it was pointed out to me). I don't have anything against 5R barrels. My Bartlein 6BR is 5R and extremely accurate, and it does not show the chattering problem. I do think the 5R barrels are easier to clean and they don't give up anything in the accuracy department. I just brought up the issue so folks are aware that reamer chatter on a 5R barrel seems to be more probable than on standard rifling. I surely hope no one else runs into this because it is a PITA, but Gordy sounds like he has run into it more than once.
I have an equal number of 5R and 5C barrels, ranging from 6AR, 6SLR, straight 284 and 7 saum. All are shooters whether f-class barrels or hunting barrels. They keep on a chuggin and clean up quite easy, even when I abuse them a bit in a p-dog town. Like them so much I just put in an order for 3 more as some are getting high in round count. Eric in DL
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