The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Guns, Politics, Gunsmithing & Reloading Gunsmithing Turning A Barrel Contour Down....Go | New | Find | Notify | Tools | Reply | |
| Turning A Barrel Contour Down.... | Login/Join |
| Administrator |
Does it actually affect accuracy? I am getting conflicting g reports from the Internet, and was hoping some of gentlemen might have first hand experience with it. | ||
|
| One of Us |
I've never shot a barrel before and after turning it down so I can't give a comparison. I have however taken a 2" OD Krieger barrel blank and machined it down to a #4 contour with integral sights at least a dozen times. All of these barrels have shot very well. My thought is that it probably affects accuracy some depending on how small of a contour you're making. A barrel maker once told me that ideally the bore would be reamed and rifling cut after the material on the outside is removed. Meaning that turning the barrel down on an already rifled barrel would affect the bore some. Then of course there's the fact that thinner barrels are more affected by heat and could be considered less accurate than heavier contours. | |||
|
| One of Us |
On a cut rifled barrel, turning it down after rifling would not matter, mostly. But, to turn down a button rifled one is a no-no due to internal stress caused by the rifling button, This is from a barrel maker. Jim Kobe 10841 Oxborough Ave So Bloomington MN 55437 952.884.6031 Professional member American Custom Gunmakers Guild | |||
|
| one of us |
This is what I'd also heard from barrel makers and read. But...Douglas (button-rifled barrels) says that there'll be no dimensional change on their barrels (internally) as long as you keep an eye on the heat. For a manual machine, take time between cuts. Or flood it with coolant if you can. They rifle, then heat treat to stress relieve, THEN profile. And they cut their thinnest profile then air gauge again after the profiling on each lot of new steel blanks to check dimensional stability. And this is pretty much what dpcd told me his experience with Douglas was as well. That he'd cut very thin profiles and had no issue with accuracy. And a guy at Trinidad told me he used Douglas button-rifled blanks to make liners for old barrels--this has to be the thinnest contour. I think there are internal stresses caused by button-rifling, but the heat treat after rifling minimizes them to where we won't be able to see the effects as long as we keep the barrel under the stress relieving temp (usually 800 deg F, I think). For button rifled barrels, I think I'd want to know if they heat treat to stress relieve AFTER rifling before turning them down. | |||
|
One of Us |
Lots of misconceptions about barrels, and the discussion arises often over the last 7 decades. Some of it based on fact, some based on supposition (much like the investment casting discussion; many still think it is little more than cast iron, which has been proven nonsense. It does persist). Anyway, the key is not how much stress is placed into the piece of steel, but how it is removed. And which is why some barrels cost $50 and some cost $500. Lower end/cost barrels, and I won't mention any names here, have to cut corners somewhere, and that is in two areas; dimensional uniformity, and stress relief. Makers that lap their barrels do so to bring the bore back to a uniform dimension; why didn't they just do the QC on each operation and that wouldn't be necessary. Bore finish is another discussion; not here. And stress relief; depending on your method and placement in the process, it may, or may not, be ok to reduce the contour. So, any blanket statement to that effect is invalid. And I always go back to Douglas; no one else can match them in quality, accuracy, and customer service. They are push buttoned on a gear driven machine. Do not use one that relies on button helix to make the twist. I have been to their factory many times; first time was in 1970. They maintain such precise uniformity that no barrel is more than .0002 (I have air gauged some) and most are less than .0001. That is without lapping. And they stress relieve twice using a proprietary method; and you can reduce the contours without issue. Their CNC lathe produces a finished barrel colder than it went in; room temp in, colder when finished; I have handled them and it is true. Some other makes will end up with a belled end. We are talking very small tolerances here. Now, to the most modern method; hammer forging; super quick, and cheap, and they work. Capital investment is huge, but one you have it, you can make barrels for a few dollars. Small custom makers can't do that. It is not possible to button rifle a barrel after it has been turned down, so which ever maker said not to turn one down after rifling is not one I would use. Anyway, to answer the OP's question; it depends on who made your barrel. | |||
|
| One of Us |
This was a heavily debated topic when I was at the Colorado School of Trades. Most of those doing the debating really did not have a firm grasp on metallurgy or machining. When I graduated and started making octagon barrels I continued to read and ask questions related to this topic. I cannot add much more than what MNR and dpcd have said, other than that I have not experienced any issues. I have made many octagon and custom profile barrels with integral features and all of them shot well after making. One integral barrel I made just to experiment was a 7x57 that was round with an integral rib. The round was .510 in diameter at the muzzle. Using a tenth bore gauge before and after machining, I could not measure a difference. I believe that many beliefs of the gun community still resonate from 50-100 years ago. Steel, machining, and manufacturing had many more hurdles that are better understood today. Nathaniel Myers Myers Arms LLC nathaniel@myersarms.com www.myersarms.com Follow us on Instagram and YouTube I buy Mauser actions, parts, micrometers, tools, calipers, etc. Specifically looking for pre-WWII Mauser tools. | |||
|
| One of Us |
Then why do they sell barrel blanks if you can't turn them down after button rifling? | |||
|
one of us |
Years ago I had a factory M77 338mag. Cut the length by 2" and turned it down as far as the smith would take it. Was a MOA shooter before and MOA after. But the muzzle rise was a killer.  As usual just my $.02 Paul K | |||
|
One of Us |
It's the hammer forged barrels you shouldn't turn down after they're beat in to their contour. I had a button rifled barrel in the shop that was small bore in the breech and big at the muzzle. It was contoured from the barrel maker. I'm guessing he ran the button after contouring. I've turned down and/or cut octagon so many cut rifled and button barrels without a single accuracy issue. It's just more expensive for me to turn it than the barrel maker. I use an air follower/steady rest and my DIY tracer.  IMG_3884 by JAMES ANDERSON, on Flickr | |||
|
| One of Us |
What I neglected to say was the barrel maker of Button rifled barrels usually profile them before rifling to maintain a consistent bore size Jim Kobe 10841 Oxborough Ave So Bloomington MN 55437 952.884.6031 Professional member American Custom Gunmakers Guild | |||
|
| One of Us |
i did it twice - turning it slow and taking just a little each time - didn't make any difference | |||
|
| One of Us |
After almost 50 years of not being able to hold down a real job..and profiling and/or turning down scores of all barrel makes, the results were about 95% successful. There were a couple I remember that visibly warped during machining..and a couple that accuracy was pretty unacceptable. Boy..to replace an integral barrel really hurts he bottom line! Personally never had a issue with Douglas or Kreiger. However, I did receive an integral job from another gunmaker that was crooked with the naked eye! (He claimed it was a Kreiger) When we chatted about this, the man who did the barrel advised me "just straighten it". Hmmmmm….Well..OK, I did and the damn thing shot mostly an inch, never outside 1.25" Oh...some might say that's not good enough......which is, frankly, the stuff that makes the grass grow green. Overall... no guarantees, but no particular fear of poor results | |||
|
| One of Us |
Barrel makers who use the button rifling process never do the rifling after contouring; that won't work. I have seen the process; you have to use a full diameter blank, do the rifling and stress relief, then contour. Not the other way round. | |||
|
| One of Us |
I've watched Boots Obermeyer cut rifle barrels, all were full blanks that I saw. Since re boring is common, I suppose with cut rifling, there is no difference? | |||
|
| One of Us |
In school we were required to profile 1 barrel. Did it 1/2 at a time, as we placed the steady at about the half way mark. We used either the 13 x 40 SB that had a taper attachment or the geared head Clausing that had a taper attachment. None saw any accuracy issues. We turned slow (about 350 -375rpm) and ran hand ground high speed turning tools. If I was to do it again I'd do it the same way, carbide would not be part of my plan. While on vacation a few years ago, I stopped into Hart Rifle Barrels as I had bought quit a few from them. They profiled/tapered on a Haas TL1 after they had been rifled and stress relieved, then stress relieved again after tapering, hand lapped, inspected, and polished using a belt sander and barrel spinner before packaging for shipment. That was the first time I had seen a pneumatic follow rest actually used. Before that, I had only seen pics and drawings. | |||
|
| one of us |
I'll put my 2 cents in FWIW. I have contoured and re-contoured a fairly large number of barrels (certainly several hundreds), and, like Duane, have found it to be mostly OK. I have had some individual barrels which warped significantly and, contrary to internet lore, these have been about half and half between cut and button rifled. If the barrel steel was not properly stress relieved, the barrel would warp. Anyone who has bought and used stress relieved steel will know that all stress relieved steel is not stress free. If the barrel is not stress relieved before machining outside, it will be likely to warp. Among the barrels I have re-contoured, I include a bunch of hammer-forged barrels. Interestingly enough, ALL of the hammer forged barrels turned well with no apparent distortion. This includes barrels from Winchester, Remington, Steyr, H-K, and Hammerli. The very best shooting BR barrel I ever had was a Hart which I turned to LV contour from a 1 1/4" blank. The very worst barrel I ever tried to contour was a buttoned barrel from a maker who did not stress relieve. The second worst was a cut-rifled barrel from a maker who also did not stress relieve. The first barrel, I threw out and replaced with a Shilen. The second one I straightened then put it in the oven through a couple of self-cleaning cycles then finished turning it. This was a carbon manganese barrel. Anything done to a barrel is going to affect accuracy, one way or another. If nothing else, the load preference is likely to change. In general, heavy barrels shoot better than light barrels so, if you make a heavy barrel lighter, it is likely to shoot groups which are a bit bigger. Given the experiences of shooters and gunsmiths though, this is not always the case. In the end, I can recount experiences and espouse beliefs but, the truth is, I KNOW less with each passing year. Regards, Bill | |||
|
| One of Us |
Yes if you are cutting grooves, you can start with a tapered blank. That is done in reboring operation; not new production. | |||
|
| One of Us |
That is the way I have seen it done. They already have a stack of drilled and reamed blanks, pulled one out and button rifled it to the desired twist. Contouring was the last step. | |||
|
One of Us |
If your barrel won't shoot after contouring...just whack your barrel  Mike Legistine actu? Quid scripsi? Never under estimate the internet community's ability to reply to your post with their personal rant about their tangentially related, single occurrence issue.  What I have learned on AR, since 2001: 1. The proper answer to: Where is the best place in town to get a steak dinner? is…You should go to Mel's Diner and get the fried chicken. 2. Big game animals can tell the difference between .015 of an inch in diameter, 15 grains of bullet weight, and 150 fps. 3. There is a difference in the performance of two identical projectiles launched at the same velocity if they came from different cartridges. 4. While a double rifle is the perfect DGR, every 375HH bolt gun needs to be modified to carry at least 5 down. 5. While a floor plate and detachable box magazine both use a mechanical latch, only the floor plate latch is reliable. Disregard the fact that every modern military rifle uses a detachable box magazine. 6. The Remington 700 is unreliable regardless of the fact it is the basis of the USMC M40 sniper rifle for 40+ years with no changes to the receiver or extractor and is the choice of more military and law enforcement sniper units than any other rifle. 7. PF actions are not suitable for a DGR and it is irrelevant that the M1, M14, M16, & AK47 which were designed for hunting men that can shoot back are all PF actions. 8. 95 deg F in Africa is different than 95 deg F in TX or CA and that is why you must worry about ammunition temperature in Africa (even though most safaris take place in winter) but not in TX or in CA. 9. The size of a ding in a gun's finish doesn't matter, what matters is whether it’s a safe ding or not. 10. 1 in a row is a trend, 2 in a row is statistically significant, and 3 in a row is an irrefutable fact. 11. Never buy a WSM or RCM cartridge for a safari rifle or your go to rifle in the USA because if they lose your ammo you can't find replacement ammo but don't worry 280 Rem, 338-06, 35 Whelen, and all Weatherby cartridges abound in Africa and back country stores. 12. A well hit animal can run 75 yds. in the open and suddenly drop with no initial blood trail, but the one I shot from 200 yds. away that ran 10 yds. and disappeared into a thicket and was not found was lost because the bullet penciled thru. I am 100% certain of this even though I have no physical evidence. 13. A 300 Win Mag is a 500 yard elk cartridge but a 308 Win is not a 300 yard elk cartridge even though the same bullet is travelling at the same velocity at those respective distances. | |||
|
| One of Us |
That must be the guy that made the button barrel that showed up in my shop with the bore diameter of the muzzle .001" larger than the breech. It was actually 3 barrels that showed up here and I told the clients I didn't want to work on them because the $ spent for me to thread, chamber, polish, blue these would be wasted due to poor accuracy. | |||
|
| one of us |
Ive had all manor of barrels rebored and turned down, knowing the risk was there, but never got a bad one back..All my rebores came back better for accuracy as a matter of fact..Most of my rebore jobs were for beautiful old Mausers with full ribs etc. so I don't know the structure of those old guns, but it worked and considering a new barrel with a full rib would cost more than my ranch truck it was a good deal..Ive had a number of std wt. pre 64 barrels turned to feather weight and no problems..I hear a lot of dismal tales on the subject, but have to wonder if its just BS because so and so said so in some magazine or on the internet,dunno!!!  Ray Atkinson Atkinson Hunting Adventures 10 Ward Lane, Filer, Idaho, 83328 208-731-4120 rayatkinsonhunting@gmail.com | |||
|
| One of Us |
I guarantee that none of your rebore jobs were done using rifling buttons. I also had a few of those barrels with the belled muzzles that guys sent me; that was in the late 70s and early 80s; no makers name on them; both 45-70. Not worth the effort to install them as you said. I did put one on a Siamese Mauser though. Obviously made with more than one shortcut in the manufacture process. | |||
|
| One of Us |
| |||
|
| One of Us |
Very true, and the reason that is important is that when the barrel stretches, if you don't adjust the tail stock, it will bend. Unless you are flooding it with coolant. | |||
|
| One of Us |
So if one wanted to have a #3 Shilen profile barrel down to a #2, who would you recommend? | |||
|
| One of Us |
Shilen | |||
|
| one of us |
I've contoured a lot of barrels, most from straight blanks, some from pre-contoured. Also fluting. I just don't understand why people insist on not re-contouring a button barrel....all you're doing is taking a few more passes where the barrel maker left off from. If it makes you feel better, after contouring, go ahead and cast a lap and re-lap the barrel. You'll feel it in the lap if the muzzle grew...if it did, lap the breech end until it's even the whole length. Done. I'm in full agreement with Duane, no guarantees, but typically there's no problem. I'm just a young pup creeping up on 50, but I have had the pleasure of spending many hours (days) in several of the fine barrel shops here in WI seeing both button and cut rifled barrels being made, along with every operation and discussion about the process. Shoot straight, shoot often. Matt | |||
|
| Administrator |
I am working out how to do it on my CNC lathe. Cannot do very long ones, but some I am sure I can. Would make life easier than on a normal lathe. | |||
|
| one of us |
Write two programs turning from opposite directions with chucking the barrel in the middle. You can end with a bit of overlap or just stop short then manually clean up that center area where the two cuts meet. For a standard 27" blank you'll have less than 15" between supports and can turn to a much smaller diameter without chatter. Not the ideal method but a decent work-around. Shoot straight, shoot often. Matt | |||
|
| One of Us |
People who insist on "not" recontouring a button rifled barrel are speaking from the position of those barrels which were not properly stress relieved during the manufacturing process. And lapping the bore back to some larger dimension is not what I consider proper; bores that need lapping have a flaw inherent to them. | |||
|
| one of us |
James Anderson, did you notice any performance or accuracy change after spiral fluting the handle on the Aloris tool post? Nice setup. | |||
|
| One of Us |
Yes  I gained a 35 nanosecond advantage during rapid tool changes. The accuracy remains within minute of squirrel at 200 yards. Since the handle is used on a manual machine, I fluted it on my manual Hardinge TMUM horizontal mill using my spiral milling attachment. It was my test subject after I built all the gears and assorted hardware for the helical gearbox years ago. When/if I add another servo amp and motor to my Milltronics CNC mill, I'll probably never need that cute little mill again. Although it's pretty slick for cutting extractor cuts. Much easier to program 1 line of G code to cut a helix than figure it out & set it up the old way. | |||
|
one of us |
I’ve recontoured many, several dozen, button rifled barrels and never had an issue with accuracy after doing so. I had one hammer-forged barrel bend dramatically while cutting it from a blank, but I kept cutting and it actually straightened back out. Go figure. John Farner If you haven't, please join the NRA! | |||
|
one of us |
TmT Was that possibly stress relief followed by stress release? | |||
|
| one of us |
Shilen did my barrels many years ago when I lived in Texas and he would not guarantee the work, but it was all good.. In Idaho Jack Belk has done mine and all worked fine mostly shot better.. For rebore High Plains did all of mine and they all shot BETTER.. I guess all told IM talking about a dozen or so barrels.. They all said the barrels could warp, but they didn,t andit seems they indicated or mentioned the secret was to go very, very slow All I know is I would recommend all three of them as they all did a fine job, as I expected they would. TClovis, I was told by Shilen that when you turn down a finished barrel from std. wt. to fwt, its automatically stress releaved????? Ray Atkinson Atkinson Hunting Adventures 10 Ward Lane, Filer, Idaho, 83328 208-731-4120 rayatkinsonhunting@gmail.com | |||
|
| Powered by Social Strata |
 | Please Wait. Your request is being processed... |
|
The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Guns, Politics, Gunsmithing & Reloading Gunsmithing Turning A Barrel Contour Down....
Visit our on-line store for AR Memorabilia