Newby question about barrels

Get or give advice on equipment, reloading and other technical issues.

Moderator: Mod

Message
Author
Barry Davies
Posts: 1183
Joined: Tue Aug 24, 2010 12:11 pm

Re: Newby question about barrels

#16 Postby Barry Davies » Mon Oct 02, 2017 7:32 am

Thanks for that info frank.My only comment is that I have always used Buttoned barrels ( Maddco ) We are currently running 5 barrels in various profiles including a fluted # 6 ( light weight ) barrel in 14 twist. It's just as good as the heavy unfluted # 7's --by good I mean better that 3/8 MOA
I guess our barrel maker has this stress relieving down to a fine art as I have never experienced any problems with barrels opening up, walking or whatever else they do under stress.
Interesting non the less as to what can happen if not relieved properly.
Barry

Frank Green
Posts: 207
Joined: Wed May 28, 2014 11:48 pm

Re: Newby question about barrels

#17 Postby Frank Green » Wed Oct 04, 2017 12:01 am

Gyro wrote:It would seem from the information you're providing us with here Frank that "you can't trust the stress relieving the button rifling barrel makers are doing to the barrel after they've pulled the button through ?"

Because if the stress relieving operation the button barrel maker does after he has rifled the bore is thorough then isn't thier barrel now in the same state as the one that's just been cut rifled ?

Or does the button rifling process induce stresses that we can't trust can ever be removed ? I would consider this a fundamental question that needs to be properly researched ?

And re dimensional uniformity and straightness is a profiled and unfired cut rifled barrel any better than a button rifled one ?

Regards Rob



Hey Rob, I'll answer your questions the best I can here.....

It would seem from the information you're providing us with here Frank that "you can't trust the stress relieving the button rifling barrel makers are doing to the barrel after they've pulled the button through ?" I'm not saying that you cannot trust that the button makers are not stress relieving the barrels etc...what I'm saying is the button rifling operation induces a lot of stress into the blank and there are no guarantees that stress relieving the blank after button rifling gets rid of all of the stress. Again like I said which includes us it is one thing that you cannot measure/check for. Single point cut rifling doesn't induce any stress into the barrel blank. That doesn't mean there cannot be any residual stress in the steel as we get it from the mill. Usually if there is will see it during contouring of the barrel which is before reaming and rifling. The barrel will typically bow. When this happens we throw it away and it doesn't even make it any further in the shop.

Because if the stress relieving operation the button barrel maker does after he has rifled the bore is thorough then isn't thier barrel now in the same state as the one that's just been cut rifled ? I will say no. Again it induces stress into the blank as well as button rifling work hardens the bore. Also I do know of button makers here in the States at least that don't even do the stress relieving in house anymore and they send it out. I wouldn't agree with this if I owned the shop. Now you are relying on a outside source that they are doing it at the proper temperatures, time etc....you have no control over it. Now you have another variable on top of a variable. I also know of lower end shops that have gotten they're steel from the mill not stress relieved to begin with or not properly done. Trying to save money is my guess. How do I know this. In the last one to two years we've done inspections on other makes of barrels for customers because of problems that they are having with melonite treatments and gun performance issues etc...

Or does the button rifling process induce stresses that we can't trust can ever be removed ? I would consider this a fundamental question that needs to be properly researched ?
It's a known fact that it is a variable that cannot be completely controlled and again it cannot be measured as far as just stress relieving as well as the heat lots of steel will be a variable as well. The only thing you can do as a test to see how much they change etc....is to make say 10 barrels in the same caliber and preferably out of the same lot. In each batch of 10 barrels make several different contours as well. Say 10pcs. of a #2 sporter contour, 10pcs. of say a med. palma contour, 10pcs. of a heavy varmint contour and 10pcs. of say 1.250" str. blanks. You would have to measure the bores before stress relieving, then after they are stress relieved to see if any changes and then after each barrel gets contoured and recheck them again.

And re dimensional uniformity and straightness is a profiled and unfired cut rifled barrel any better than a button rifled one ? Not sure how you are/what you are asking here. If you are asking if cut rifled barrels are dimensionally more uniform then a button barrel? I will say yes. Weather it's been fired or not on a average basis. Could a cut rifle barrel change? Sure as you are dealing with the steel being a variable. What I've always seen is and as well as feed back I get from ammunition makers that we make test barrels for is the cut rifled barrels are more consistent in uniformity from one barrel to the next vs. a button barrel.

Hope that helps in answering your questions.

Later, Frank

Frank Green
Posts: 207
Joined: Wed May 28, 2014 11:48 pm

Re: Newby question about barrels

#18 Postby Frank Green » Wed Oct 04, 2017 12:05 am

Gyro wrote:BTW Frank I don't wish to drag u into a cut Vs button debate. You have been good enough to provide a bunch of good information here. My current buttoned barrel seems to be going well such that when it doesn't i can be very sure it's me ! Regards Rob.


No problem Rob! So no worries and no offense taken.

I will say this as well. I've been offered jobs at button barrel makers but I know in depth the differences between the two methods and I couldn't work for a maker and sell a product I don't believe in and look a customer in the face and say we are making the best etc....so I've politely have turned down the job offers.

Button barrels can be very good performers with no issues etc....they have proven themselves. I just don't see the consistency in them all the time.

Later, Frank

Frank Green
Posts: 207
Joined: Wed May 28, 2014 11:48 pm

Re: Newby question about barrels

#19 Postby Frank Green » Wed Oct 04, 2017 12:08 am

Barry Davies wrote:Thanks for that info frank.My only comment is that I have always used Buttoned barrels ( Maddco ) We are currently running 5 barrels in various profiles including a fluted # 6 ( light weight ) barrel in 14 twist. It's just as good as the heavy unfluted # 7's --by good I mean better that 3/8 MOA
I guess our barrel maker has this stress relieving down to a fine art as I have never experienced any problems with barrels opening up, walking or whatever else they do under stress.
Interesting non the less as to what can happen if not relieved properly.
Barry


Your welcome Barry!

Later, Frank

jasmay
Posts: 981
Joined: Fri Sep 28, 2012 9:26 pm

Re: Newby question about barrels

#20 Postby jasmay » Wed Oct 04, 2017 2:13 pm

Frank, I'd just like to say a big thanks, your input here is invaluable to Australian shooters, it's pretty rare we have the privilege of having a manufacture share the minutiae of their work, thanks again!!

BATattack
Posts: 953
Joined: Mon Dec 29, 2008 10:29 pm

Re: Newby question about barrels

#21 Postby BATattack » Wed Oct 04, 2017 2:24 pm

gyro.

If you had two pieces of 20mm thick flat bar and you wanted them to be 15mm thick.

you take one and put it on the mill and gradually deck it down to 15mm in .5mm passes with cutting fluid running over it. You now have a piece of flat bar 15mm thick

you take your second piece of 20mm flat bar and take it to the bench where you bash it with a hammer and until you can swage it down to 15mm thick.

you now have two pieces of flat bar that are 15mm thick. . . . success! what one do you think has more potential for residual stress? if the cold hammer swaged bar was "stress relived" do you think there is still potential for it to have residual stress?

Frank Green
Posts: 207
Joined: Wed May 28, 2014 11:48 pm

Re: Newby question about barrels

#22 Postby Frank Green » Fri Oct 06, 2017 6:34 am

BATattack wrote:gyro.

If you had two pieces of 20mm thick flat bar and you wanted them to be 15mm thick.

you take one and put it on the mill and gradually deck it down to 15mm in .5mm passes with cutting fluid running over it. You now have a piece of flat bar 15mm thick

you take your second piece of 20mm flat bar and take it to the bench where you bash it with a hammer and until you can swage it down to 15mm thick.

you now have two pieces of flat bar that are 15mm thick. . . . success! what one do you think has more potential for residual stress? if the cold hammer swaged bar was "stress relived" do you think there is still potential for it to have residual stress?


BATattack, You do bring up a very good and practical way of looking at it and I will add to it.

Right now a leading arms manufacturer is doing testing and sorry but I cannot say as to who the maker is. They're factory guns have hammer forged barrels on them. You can get our barrels on the guns as an upgrade option.

Anyways they are trying to get the factory hammer forged barrels to shoot as good as ours and they are doing testing right now (I know as they just ordered more barrels from us in both .30cal. and .224cal.). A good barrel for the factory hammer forged barrel the has been only able to shoot 1moa. They start with 1.250" diameter straight blanks fitted up to a high end bolt action receiver. I won't name exact names but receivers like BAT Machine, Defiance etc...bedded in a fiberglass stock like a Mcmillan or Manners etc...anyways the straight blank starts out shooting 1moa. Then they've been taking the barrels off and recontouring them. The smaller they make the contour and after each time the barrel keeps shooting worse and worse. I don't know if they are stress relieving the blank each time or not or even if it's being done in the first place. It's a question I have to ask but what is happening each time is the bore is shifting and the sizes keep opening up.

Later, Frank

Bigtravoz
Posts: 109
Joined: Sat Apr 22, 2017 7:43 pm

Re: Newby question about barrels

#23 Postby Bigtravoz » Thu Feb 01, 2018 7:24 pm

As a tool maker, with much fitting and turning experience Frank it has been my experience that cutting and boring does not induce stress upon the steel it does the opposite, whereby the removal of material allows any stresses within the remaining material to “show” themselves and influence the other remaining material that isn’t as stressed, if this makes sense. As part of my trade we look at normalisation of the material and also how to apply tension to make what would otherwise be a sloppy mess into something which will hold form either at high revolutions or when under load. For instance a circular saw cut from a sheet of steel will become sloppy at rpm and will not cut accurately however if you induce tension into the body, by hammering or rolling, the cutting edge will then remain tight and run true. Now I can see how forcing a button through a bore can and definitely would induce tension/stress into the steel, as there are forces of expansion, contraction and compression all at work in a very small area and under a considerable amount of force. Personally I would think that a cut barrel would be the better relieved piece of steel but the compression of the surface from button rifling would leave a more smooth and less fouling surface if(and I must stress the if) it’s done correctly. I also wonder if some of the stress imparted into the steel would also make it somewhat “stiffer” reducing the harmonic vibrations and creating a smaller spread on point of impact through load variations. Unfortunately my gun barrel drilling has been confined to drilling plastics so I don’t have the experience with long boring of steel rods and firing projectiles through them to be able to have tested a lot of my theories and thoughts about the topic. I am however glad my simple question about Douglas barrels has spurned such a conversation.

Edit: also inducing too much tension in the wrong areas will also cause a sloppy mess.
2nd edit: I can also understand how repetitive harmonic vibrations and heat and pressure of forcing a projectile down it could essentially “relieve “ stresses in the compressed/stressed material thus creating a barrel that would gradually degrade or show a change in point of impact.

Bigtravoz
Posts: 109
Joined: Sat Apr 22, 2017 7:43 pm

Re: Newby question about barrels

#24 Postby Bigtravoz » Thu Feb 01, 2018 7:50 pm

Frank Green wrote:
Barry Davies wrote:G'day Frank,
What about drilling and reaming prior to rifling would not that introduce stresses? I would have thought it would but then I am not a barrel maker.
Barry


G'day Barry, Drilling and reaming doesn't induce any stress into the blank. Reaming only takes out approx. .007" to .008" getting the barrel ready for prelapping and rifling. Your not doing a heavy cut etc...on it during this process or during cut rifling. During rifling we are only taking out approx. .0001" of a cut per pass in one groove at a time.

If there is any residual stress in the barrel blank we will see it during turning/contouring. The barrel will bow/bend on you. If this happens the barrel doesn't even make it to bore reaming etc...and we throw it away.

Button rifle makers cannot contour a barrel before reaming and rifling etc...

The one thing no barrel maker can measure for is any stress in the material. The only way to watch for it is during the manufacturing process.

Hope that answers your question?

Later, Frank


This makes full sense and in essence is what I was touching on in my last post.

Bigtravoz
Posts: 109
Joined: Sat Apr 22, 2017 7:43 pm

Re: Newby question about barrels

#25 Postby Bigtravoz » Thu Feb 01, 2018 7:55 pm

Frank Green wrote:
BATattack wrote:gyro.

If you had two pieces of 20mm thick flat bar and you wanted them to be 15mm thick.

you take one and put it on the mill and gradually deck it down to 15mm in .5mm passes with cutting fluid running over it. You now have a piece of flat bar 15mm thick

you take your second piece of 20mm flat bar and take it to the bench where you bash it with a hammer and until you can swage it down to 15mm thick.

you now have two pieces of flat bar that are 15mm thick. . . . success! what one do you think has more potential for residual stress? if the cold hammer swaged bar was "stress relived" do you think there is still potential for it to have residual stress?


BATattack, You do bring up a very good and practical way of looking at it and I will add to it.

Right now a leading arms manufacturer is doing testing and sorry but I cannot say as to who the maker is. They're factory guns have hammer forged barrels on them. You can get our barrels on the guns as an upgrade option.

Anyways they are trying to get the factory hammer forged barrels to shoot as good as ours and they are doing testing right now (I know as they just ordered more barrels from us in both .30cal. and .224cal.). A good barrel for the factory hammer forged barrel the has been only able to shoot 1moa. They start with 1.250" diameter straight blanks fitted up to a high end bolt action receiver. I won't name exact names but receivers like BAT Machine, Defiance etc...bedded in a fiberglass stock like a Mcmillan or Manners etc...anyways the straight blank starts out shooting 1moa. Then they've been taking the barrels off and recontouring them. The smaller they make the contour and after each time the barrel keeps shooting worse and worse. I don't know if they are stress relieving the blank each time or not or even if it's being done in the first place. It's a question I have to ask but what is happening each time is the bore is shifting and the sizes keep opening up.

Later, Frank


I also have somewhat of an understanding of what would be causing this and it was essentially uncovered many many moons ago by Reynolds and Columbus when making steel tubing for bicycle frames, where the stiffness of any given steel is a given and regardless of what additives are included in the steel there is only so much strength/stiffness in it and the thinner it becomes the less strength it has and the more whippy it becomes. The study also showed the relative strength to dimension ratios were virtually the same from mild steel right through to their special alloy steels, and that there was a point where the thickness of material would fail as easily in mild steel as it would in their special alloys. I know I have not worded this as well as I would like to or as correctly as I need to but cannot find the information I need to explain it correctly at this point in time.

Bigtravoz
Posts: 109
Joined: Sat Apr 22, 2017 7:43 pm

Re: Newby question about barrels

#26 Postby Bigtravoz » Thu Feb 01, 2018 8:41 pm

Or does the button rifling process induce stresses that we can't trust can ever be removed ? I would consider this a fundamental question that needs to be properly researched ?


Yes it certainly would be the case and I am sure I could find evidence of it in one of my many books on the subject gyro. When pulling a button through a bore there are multiple stresses at play all at once, the material is being forced to expand around the button in differing amounts (lands and grooves) the material in the grooves is being forced into the lands, the whole lot then relaxes after the button passes it and while the button is moving forward it drags/smudges material as it goes. There is also the potential for variance in load/force due to variations in the material, build up of material being forced at the lead of the button, or from irregularities in the initial boring prior to the broaching with the button.

Frank Green
Posts: 207
Joined: Wed May 28, 2014 11:48 pm

Re: Newby question about barrels

#27 Postby Frank Green » Wed Feb 07, 2018 1:56 am

Bigtravoz wrote:As a tool maker, with much fitting and turning experience Frank it has been my experience that cutting and boring does not induce stress upon the steel it does the opposite, whereby the removal of material allows any stresses within the remaining material to “show” themselves and influence the other remaining material that isn’t as stressed, if this makes sense. As part of my trade we look at normalisation of the material and also how to apply tension to make what would otherwise be a sloppy mess into something which will hold form either at high revolutions or when under load. For instance a circular saw cut from a sheet of steel will become sloppy at rpm and will not cut accurately however if you induce tension into the body, by hammering or rolling, the cutting edge will then remain tight and run true. Now I can see how forcing a button through a bore can and definitely would induce tension/stress into the steel, as there are forces of expansion, contraction and compression all at work in a very small area and under a considerable amount of force. Personally I would think that a cut barrel would be the better relieved piece of steel but the compression of the surface from button rifling would leave a more smooth and less fouling surface if(and I must stress the if) it’s done correctly. I also wonder if some of the stress imparted into the steel would also make it somewhat “stiffer” reducing the harmonic vibrations and creating a smaller spread on point of impact through load variations. Unfortunately my gun barrel drilling has been confined to drilling plastics so I don’t have the experience with long boring of steel rods and firing projectiles through them to be able to have tested a lot of my theories and thoughts about the topic. I am however glad my simple question about Douglas barrels has spurned such a conversation.

Edit: also inducing too much tension in the wrong areas will also cause a sloppy mess.
2nd edit: I can also understand how repetitive harmonic vibrations and heat and pressure of forcing a projectile down it could essentially “relieve “ stresses in the compressed/stressed material thus creating a barrel that would gradually degrade or show a change in point of impact.


I think we are basically saying the same thing but in different terms....?

The secondary machining operations like turning and fluting etc...the machining operation will not induce stress but it will relieve it.

Button rifling doesn't necessarily give you a smoother bore. If they ream the bore and the bore reamer leaves heavy/deep grooves the button operation will just force the marks down into the grooves as well. In some cases it helps iron them out per say/make them smoother and this is the argument some button makers make in saying they don't need to finish lap the barrels because the button rifling smooths them out. From what I see I don't agree with that statement.

It goes back to the maker paying attention to all aspects of the manufacturing process.

Later, Frank

Frank Green
Posts: 207
Joined: Wed May 28, 2014 11:48 pm

Re: Newby question about barrels

#28 Postby Frank Green » Wed Feb 07, 2018 2:04 am

Bigtravoz wrote:Or does the button rifling process induce stresses that we can't trust can ever be removed ? I would consider this a fundamental question that needs to be properly researched ? Correct....button rifling induces a lot of stress into the blank and you are correct that when the steel/blank gets stress relieved again there are no guarantee's that it is all removed/relieved properly.


Yes it certainly would be the case and I am sure I could find evidence of it in one of my many books on the subject gyro. When pulling a button through a bore there are multiple stresses at play all at once, the material is being forced to expand around the button in differing amounts (lands and grooves) the material in the grooves is being forced into the lands, the whole lot then relaxes after the button passes it and while the button is moving forward it drags/smudges material as it goes. There is also the potential for variance in load/force due to variations in the material, build up of material being forced at the lead of the button, or from irregularities in the initial boring prior to the broaching with the button.
Also correct....the different lots of steel are a variable as well as the diameter of the blanks and the button size. You go from a 1.280" diameter blank for example to a 1.5"diameter bar to a 2" diameter bar and even though technically you are doing the same caliber in all of them you will need a different button size because the different diameters of steel (the heavier diameters) if you keep using the same button will tighten up on you. So they normally have to go to a bigger diameter button for the larger blanks or the bore will tighten up on you.

Just seen this late last year where we we're asked to inspect some pressure test barrels for a ammo maker. They had received some test barrels from a button maker but the pressures where running around 8k psi higher and driving up the velocity about 150-200fps. faster as well. Turned out the button maker use the same button for a bolt gun barrel and ran it thru a 2" diameter blanks. The bore and grooves tightened up .0005" undersize min. bore spec. Which in turn was driving up the pressures and the cause of the problem.

Later, Frank

Gyro
Posts: 349
Joined: Sat Jun 10, 2017 2:44 pm
Location: New Zealand

Re: Newby question about barrels

#29 Postby Gyro » Wed Feb 07, 2018 3:16 am

Bigtravoz wrote:
Frank Green wrote:
BATattack wrote:gyro.

If you had two pieces of 20mm thick flat bar and you wanted them to be 15mm thick.

you take one and put it on the mill and gradually deck it down to 15mm in .5mm passes with cutting fluid running over it. You now have a piece of flat bar 15mm thick

you take your second piece of 20mm flat bar and take it to the bench where you bash it with a hammer and until you can swage it down to 15mm thick.

you now have two pieces of flat bar that are 15mm thick. . . . success! what one do you think has more potential for residual stress? if the cold hammer swaged bar was "stress relived" do you think there is still potential for it to have residual stress?


BATattack, You do bring up a very good and practical way of looking at it and I will add to it.

Right now a leading arms manufacturer is doing testing and sorry but I cannot say as to who the maker is. They're factory guns have hammer forged barrels on them. You can get our barrels on the guns as an upgrade option.

Anyways they are trying to get the factory hammer forged barrels to shoot as good as ours and they are doing testing right now (I know as they just ordered more barrels from us in both .30cal. and .224cal.). A good barrel for the factory hammer forged barrel the has been only able to shoot 1moa. They start with 1.250" diameter straight blanks fitted up to a high end bolt action receiver. I won't name exact names but receivers like BAT Machine, Defiance etc...bedded in a fiberglass stock like a Mcmillan or Manners etc...anyways the straight blank starts out shooting 1moa. Then they've been taking the barrels off and recontouring them. The smaller they make the contour and after each time the barrel keeps shooting worse and worse. I don't know if they are stress relieving the blank each time or not or even if it's being done in the first place. It's a question I have to ask but what is happening each time is the bore is shifting and the sizes keep opening up.

Later, Frank


I also have somewhat of an understanding of what would be causing this and it was essentially uncovered many many moons ago by Reynolds and Columbus when making steel tubing for bicycle frames, where the stiffness of any given steel is a given and regardless of what additives are included in the steel there is only so much strength/stiffness in it and the thinner it becomes the less strength it has and the more whippy it becomes. The study also showed the relative strength to dimension ratios were virtually the same from mild steel right through to their special alloy steels, and that there was a point where the thickness of material would fail as easily in mild steel as it would in their special alloys. I know I have not worded this as well as I would like to or as correctly as I need to but cannot find the information I need to explain it correctly at this point in time.


Lads if u want the 'formal ' explanation of this material stiffness being alluded to here the work/understanding of this property of a material was developed a VERY long time ago and is widely referred to as "Youngs Modulus " . It's also explained as a materials "Modulus of Elasticity ". These days it's loosely called the "E" value.

Understanding material stiffness is crucial from a design perspective !!! Those of us ( like me ) who once thought I could make a long boring bar from say HSS had to learn that was not the way to increase stiffness. Ya gotta pick another material to make that long boring bar like say Molybdenum. Amazon sells it.

Huge subject and one that greatly interests me especially as I love working with carbon fiber. Use carbon fiber the right way and it is VERY strong AND stiff.


Return to “Equipment & Technical”

Who is online

Users browsing this forum: No registered users and 9 guests