Barrels

[Frank Green]

I believe that if you had a group of barrels that measured perfect in every respect that some would shoot better than others and that the only way to find them would be to try them all. It may be that the one variable that we cannot see through ordinary means is residual stress. In the case of cut barrels it comes from the steel mill, and in the case of button barrels that are stress relieved it is the result of an imperfect process. I have seen some evidence of the latter.

One thing no barrel maker can measure for is residual stress in the barrel blank/steel.

I won't speak for all barrel makers and how they get they're steel. Ours comes heat treated and double stress relieved. We don't induce any stress into the barrel during reaming or rifling. If a barrel blank has a lot of stress in it, it will show up during the contouring which is done before reaming and rifling. If we're going to lose the blank it will be at this point if it has stress in it.

Button makers have to rifle the barrel as a barrel blank. Cannot have no shape/contour etc....on it. After button rifling they need to restress relieve the blank again because button rifling induces stress into the blank. Restress relieving the blank doesn't guarantee that you got any residual stress out. Again you cannot measure for it. During the contouring operation, or even cutting and crowning the muzzle, threading the muzzle, fluting etc...that during the secondary machining operation if you hit a residual stress point it will relieve the stress and the bore will open up on you. Can open up only a .0001" and I've seen them change an easy .0005" to even +.001" bigger. Either way when that happens you cannot make it go back! It is what it is. Same goes for during shooting. I've seen where a button barrel got hot enough to relieve itself and the bore went sour.

Later, Frank

 

[jackie schmidt]

Ont thing no barrel maker can measure for is residual stress in the barrel blank/steel.

I won't speak for all barrel makers and how they get they're steel. Ours comes heat treated and double stress relieved. We don't induce any stress into the barrel during reaming or rifling. If a barrel blank has a lot of stress in it, it will show up during the contouring which is done before reaming and rifling. If we're going to lose the blank it will be at this point if it has stress in it.

Button makers have to rifle the barrel as a barrel blank. Cannot have no shape/contour etc....on it. After button rifling they need to restress relieve the blank again because button rifling induces stress into the blank. Restress relieving the blank doesn't guarantee that you got any residual stress out. Again you cannot measure for it. During the contouring operation, or even cutting and crowning the muzzle, threading the muzzle, fluting etc...that during the secondary machining operation if you hit a residual stress point it will relieve the stress and the bore will open up on you. Can open up only a .0001" and I've seen them change an easy .0005" to even +.001" bigger. Either way when that happens you cannot make it go back! It is what it is. Same goes for during shooting. I've seen where a button barrel got hot enough to relieve itself and the bore went sour.

Later, Frank

Thanks for the info, Frank.
What you said is one reason I will avoid doing any machine work on a barrel's OD aside from what ever it takes to get it in the action and install a tuner.

 

[Michael Huebner]

Ont thing no barrel maker can measure for is residual stress in the barrel blank/steel.

I won't speak for all barrel makers and how they get they're steel. Ours comes heat treated and double stress relieved. We don't induce any stress into the barrel during reaming or rifling. If a barrel blank has a lot of stress in it, it will show up during the contouring which is done before reaming and rifling. If we're going to lose the blank it will be at this point if it has stress in it.

Button makers have to rifle the barrel as a barrel blank. Cannot have no shape/contour etc....on it. After button rifling they need to restress relieve the blank again because button rifling induces stress into the blank. Restress relieving the blank doesn't guarantee that you got any residual stress out. Again you cannot measure for it. During the contouring operation, or even cutting and crowning the muzzle, threading the muzzle, fluting etc...that during the secondary machining operation if you hit a residual stress point it will relieve the stress and the bore will open up on you. Can open up only a .0001" and I've seen them change an easy .0005" to even +.001" bigger. Either way when that happens you cannot make it go back! It is what it is. Same goes for during shooting. I've seen where a button barrel got hot enough to relieve itself and the bore went sour.

Later, Frank

Frank,
At what point do you believe it makes a difference? Is it over .0005 or greater? What would fluting a barrel afterwards typically induce in a cut and button rifled barrels?
I am just curious as unless the blank or barrel was sent back for measurement to someone like yourself, we would never really know. We can only see what happens on the Target.

Example;
I had a button rifled blank from a well known maker that started as a Heavy Varmint 26", 6lb + barrel and it had a rough spot which collected copper mid length. It was a Hummer which I didn't know at the time but found out very quickly and managed to take advantage of this (I am a believer as have now owned one).

I did everything you shouldn't do, it was rechambered to different actions and in the end fluted fairly aggressively to reach Australian Sporter so ended up under 4lbs and 20" long. This was over a 6yr period.

After all this work it was always a hummer. Truly amazing barrel. Worn out now with 3000+ rounds through it

That's why I always shoot a barrel and would never send one back because it didn't look right, or coppers a bit in a spot etc

So I am just interested in your thoughts

Michael

 

[zippy06]

I don't know if that's right but it's a pretty good indication. I thought that the flags could rotate an hour either way and the shot still go in the hole. Truth is, if you had a barrel that would do both you would have a pretty good barrel. What I do know for sure is...if you get away with such a shot you really need to shoot a sighter to make sure before you shoot another record shot regardless of what barrel you have.

Gee Wilbur. I am not sure about that extra sighter stuff. Last score match, I wasted 4 bullseyes on checking with sighter....
Lowell always said "just shootem' ".....Then at his funeral Joe said Lowell shot a lot of culled bullets. Ones he would not sell.
This summer. I had a bunch of culled bullets. Mixed 10 of each. Good bad....Holy cow. 200y score 198/200. The 2 out were barely out...

 

[Frank Green]

Frank,
At what point do you believe it makes a difference? Is it over .0005 or greater? What would fluting a barrel afterwards typically induce in a cut and button rifled barrels?
I am just curious as unless the blank or barrel was sent back for measurement to someone like yourself, we would never really know. We can only see what happens on the Target.

Example;
I had a button rifled blank from a well known maker that started as a Heavy Varmint 26", 6lb + barrel and it had a rough spot which collected copper mid length. It was a Hummer which I didn't know at the time but found out very quickly and managed to take advantage of this (I am a believer as have now owned one).

I did everything you shouldn't do, it was rechambered to different actions and in the end fluted fairly aggressively to reach Australian Sporter so ended up under 4lbs and 20" long. This was over a 6yr period.

After all this work it was always a hummer. Truly amazing barrel. Worn out now with 3000+ rounds through it

That's why I always shoot a barrel and would never send one back because it didn't look right, or coppers a bit in a spot etc

So I am just interested in your thoughts

Michael

There are a lot of variables to contend with. Let's throw in bullet diameter as well has jacket hardness. If you have a barrel per say that the grooves are (I'm going to stick with .30cal. for simple numbers) where the grooves are .3084" diameter and you get a box of bullets that are fat at say .3084" or .3085". Probably won't see any issues. This is assuming the bore and groove are uniform for size over the length of the barrel. Now switch it around....you get a box of bullets that are .3078" diameter. If the latter happens it does effect accuracy but then we go back to what is your accuracy requirement. Might not effect it enough to worry about it but then it might. What I've learned recently about bullets and this probably more pertains to bullet failure problems but jacket hardness. I've been told that jacket hardness is in theory a concern but very hard to measure. The different lots of material I know can have an effect on fouling. Does jacket hardness effect how a fat or skinny bullet goes thru the barrel and does it effect accuracy?

Also where does the bore open up? If the bore opens up at the worst possible spot which is the crown of the barrel it will effect accuracy. I wouldn't be concerned about a .0001" or so but say .0003" to .0005" I'll say yes.

Fluting a barrel? I myself would never flute a button barrel. Again residual stress in the blank, you flute it you take a gamble on the bore going sour and where it goes sour and how much it opens up can have a big impact on the accuracy.

I personally have not seen a cut rifled barrels bore go sour from fluting dimensionally wise. Not saying it cannot happen as I will thrown in Murphy's law here but I will say though I do believe in that you flute a cut barrel or a button barrel etc...you flute it to deep and you can cause harmonic/vibrations issues which leads to accuracy issues. One of our top customers performed a test about 8 years back. Same contour barrels but one caliber was .30cal. for .300wm and the other caliber was .338 Lapua. They ran the test with 10 barrels of each caliber if memory serves me right. They fluted the barrels really deep (I won't give the number) as they had to come in under a specific with limit. The .30cal. barrels had no issues but two of the .338 barrels would at random throw a shot or two in every group. I want to say 10 shot groups but they couldn't tell you when it would happen. It would just happen. The difference between the barrels I believe was due to the depth of the flutes and going from .30cal. to .338cal. you lost .030" of wall thickness. For reasons like this not to mention any safety concerns we have a min. depth on flutes that we do and recommend. It's based more on contour then caliber. After this test they dropped the fluting spec. to make weight and changed the contour to make weight and had no issues.

 

[David Apple]

Kostyshyn barrels were known to be 'not very straight.' I sold a Farley with a Kostyshyn barrel on it with 4500 rounds which then won the 200-300 Group Nationals . So much for straight barrels.

 

[Jim Pag]

Kostyshyn barrels were known to be 'not very straight.' I sold a Farley with a Kostyshyn barrel on it with 4500 rounds which then won the 200-300 Group Nationals . So much for straight barrels.

Jesus David. You've sold more than one rifle that has gone on to win multiple National event. You gotta stop that. LMOA! Merry Christmas buddy.

 

[Pete Wass]

I had a Borden

Kostyshyn barrels were known to be 'not very straight.' I sold a Farley with a Kostyshyn barrel on it with 4500 rounds which then won the 200-300 Group Nationals . So much for straight barrels.

with a Kostyshyn barrel on it that was whopping big bore except for the two inch tight choke a the muzzle and it was a hammer. Only 30 Cal barrel I have ever seen made like that but it shot superbly. It's a shame Craig didn't hang in there. I have sold high mileage rifles that have won Nationals and one set at least one record but much of that was driver dependent, no question in my mind.

Regarding the observations we can provide is any match for what someone who is testing with sophisticated measuring equipment along with testing can provide. Many of us have seen exceptions to all the rules I think but if straightness is a guarantee, why wouldn't anyone want to be there?

I really don't think anyone is seeking the crookedest barrels they can find, Do you?

Pete

 

[Pete Wass]

Only the best for my friends

I know about those hammer barrels, Pete.
You sell the good stuff.
Thank you and Merry Christmas.

It was my pleasure seeing you win the Nationals F. Merry Christmas to you as well.

Pete

 

[Frank Green]

Thanks for the info, Frank.
What you said is one reason I will avoid doing any machine work on a barrel's OD aside from what ever it takes to get it in the action and install a tuner.

Jackie, Your welcome!

Check these video's out....

Here ya go....

https://www.youtube.com/watch?v=CUm_YXzJJOU

The first one above shows the muzzle going sour/opening up during/after threading. All of the first barrels are button rifled. The last two are ours. I had nothing to do with making the video's in any way. On the muzzle threading video Robert's point is not to hack on this barrel maker or that barrel maker but wants to show what can happen during muzzle threading and his point is that if you have to thread the muzzle to make the threads as large as you possibly can. In one way it's not a fair video as he cut a larger thread on one of our barrels if I remember correctly but with saying that we've cut threads on ammunition test barrels where the steel started out at 2.280" diameter and we had to cut a 5/8-24 thread for the suppressor attachment after chambering, contouring etc...and the bores didn't go sour at all and we have to supply an inspection report on chamber dimensions and bore and groove sizes with the barrels when they ship. Can it happen with a cut barrel? Sure I'll throw Murphy's law in on this one but I personally haven't seen it.

The next one is a button barrel. Watch real closely right about the 8 second mark when the button goes into the barrel. Watch the face of the barrel blank deform. You can see it better starting at the 6:20 mark and also look at the
face of the barrel at the 6:40 mark. You can see the steel is deformed.

Also at the 5:10 mark they talk about straightening the steel bars. Bad! You never want to straighten a barrel blank. Especially after it's been finished. Trying to straighten the barrel blanks induces more stress into the steel.
And some guys wonder why the POI shift on some barrels!

https://www.youtube.com/watch?v=0XSkhtcAL1w

Enjoy the videos!

Later, Frank

 

[Pete Wass]

I thought the second Youtube

was interesting in that the presenter emphasized STRAIGHT, making sure the barrels were straight. We all have seen some that weren't.

Pete

 

[Frank Green]

was interesting in that the presenter emphasized STRAIGHT, making sure the barrels were straight. We all have seen some that weren't.

Pete

The questions I would have for them would be....

Is the steel coming in stress relieved to begin with? I ask because it's a very important question and will relate to my last question......

How are they measuring the straightness of the bar? What's the tolerance they are running with?

Are they checking for straightness after drilling?

After reaming and rifling?

What/how are they measuring the straightness of the hole?

After stress relieving? And.....After contouring?

Again if they are straightening weather it be the bar or the contoured rifled barrel either way I'll guarantee they are inducing stress into the barrel.

I won't name the maker but we inspected several barrels in a AR profile/contour. We had to do a before and after process inspection. The barrel maker was claiming that the finishing companies for finishing process (this came from the finisher to us) was causing the bores to change size and it was the finishing companies fault so they wanted the finisher to eat the cost on the barrels. The thing was where ever the barrel changed contour size the bore and groove dimensions had already changed from the machining during contouring. There fore there was no uniformity to begin with. When the finish was applied and heat treated (basically the short version of the process) the bore and grooves where yet changing again because the finishing process was relieving residual stresses in the finished barrel. So after seeing this and my opinion being asked as to why it would do that both ways.....my only guess is the steel wasn't stress relieved as it came from the mill. I told the finisher to get a copy of the material inspection report. The bore dimensions changed again during the contouring process and changed yet again after the finishing process. The dimensions varied an easy +.001" in different areas in the barrels.

Also checked some hammer forged barrels by a well known firearms manufacturer a few years back. Again no consistency in bore and groove dimensions over the length of the barrel.

Happy New Year to all!

Later, Frank

 

[Frank Green]

I like the way you do it Frank.
I've won more with Bartlein Barrels than with any others.

Thanks FBecigneul!

 

[Pete Wass]

Question Frank,

Is it possible to begin with stress free bar stock and keep the stress out as the process goes along and end up with straight barrels with concentric holes through them on purpose, not just by accident? Lets say a straight blank 1" in diameter. Is stress free stock even or ever available?

Thanks,

pete

 

[Frank Green]

Is it possible to begin with stress free bar stock and keep the stress out as the process goes along and end up with straight barrels with concentric holes through them on purpose, not just by accident? Lets say a straight blank 1" in diameter. Is stress free stock even or ever available?

Thanks,

pete

Off hand I'm going to say no. Again you cannot measure for it per say at this point in time that I'm aware of. Some information was just giving to me on this subject but have to check it out.

If the steel mill could make and guarantee us stress free material what would all of be willing to pay for it? I'm sure it would come with a cost. If our costs go up the product cost is going to go up as well.

Again the most stress free way to rifle a barrel is by the single point cut rifling method. The only real place I possibly see us inducing stress/or relieving stress in the blank is during the contouring operation. If it happens there one it's before reaming and rifling and second we throw the blank away so it never makes it to rifling to begin with.

Later, Frank

 

[glp]

Yea Pete

with a Kostyshyn barrel on it that was whopping big bore except for the two inch tight choke a the muzzle and it was a hammer. Only 30 Cal barrel I have ever seen made like that but it shot superbly. It's a shame Craig didn't hang in there. I have sold high mileage rifles that have won Nationals and one set at least one record but much of that was driver dependent, no question in my mind.

Regarding the observations we can provide is any match for what someone who is testing with sophisticated measuring equipment along with testing can provide. Many of us have seen exceptions to all the rules I think but if straightness is a guarantee, why wouldn't anyone want to be there?

I really don't think anyone is seeking the crookedest barrels they can find, Do you?

Pete

but even richard petty couldn't win a race behind the wheel of a Pinto.

 

[jackie schmidt]

Is it possible to begin with stress free bar stock and keep the stress out as the process goes along and end up with straight barrels with concentric holes through them on purpose, not just by accident? Lets say a straight blank 1" in diameter. Is stress free stock even or ever available?

Thanks,

pete

Pete, most of the irregularities you see in a Barrel's ID are the result of the initial drilling operation. Despite the great strides that have been made through the years, the act of getting a 100 percent true and straight hole through something like a Rifle barrel is still a great challenge. Every other operation, the reaming, the rifling, and the lapping will tend to follow this initial drilled hole.

Figuring out why Gun drills seem to take a mind of their own and drift off of their initial course has always been a source of aggravation. Often, the hole might end up true with each end, but found to wonder off in different directions as it courses through the material.

The culprit might be a small difference in RC hardness encountered by the drill as it advances. It could be a small buildup of shavings that for whatever reason did not flush properly.. In simple terms, there might be a few things that would cause a gun drill to follow a predetermined true path through a blank, and a multitude of things that would cause it not to.

The truth is, I am amazed at how truly straight the ID's of barrels that come from our top quality manufacturers are.

Stress will cause a piece of material to change when subjected to a certain actions after all of the finished machining processes have been performed. Heat is the first one to come to mind, but strain and vibration can also be a contributing factor.

We deal with this on a constant basis at my shop. When machining long shafts, you get a first hand view as to the amount of stress that can be induced into a piece of material through machining, and the amount that can be released. We are constantly having to straighten them throughout the entire marching steps, so that in the end, we end up with a long shaft that is truly straight.

But we rarely have to deal with an ID. 95 percent of the shafts we machine are solid. On occasion, we will have a shaft that has a hole through the center for a control rod or hydraulic system to operate a variable pitch Propeller system. We generally have these holes Trepanned and Reamed with the hope it will end up somewhere in the middle and be reasonably straight with it's self.

 

[Pete Wass]

Thanks Jackie

Pete, most of the irregularities you see in a Barrel's ID are the result of the initial drilling operation. Despite the great strides that have been made through the years, the act of getting a 100 percent true and straight hole through something like a Rifle barrel is still a great challenge. Every other operation, the reaming, the rifling, and the lapping will tend to follow this initial drilled hole.

Figuring out why Gun drills seem to take a mind of their own and drift off of their initial course has always been a source of aggravation. Often, the hole might end up true with each end, but found to wonder off in different directions as it courses through the material.

The culprit might be a small difference in RC hardness encountered by the drill as it advances. It could be a small buildup of shavings that for whatever reason did not flush properly.. In simple terms, there might be a few things that would cause a gun drill to follow a predetermined true path through a blank, and a multitude of things that would cause it not to.

The truth is, I am amazed at how truly straight the ID's of barrels that come from our top quality manufacturers are.

Stress will cause a piece of material to change when subjected to a certain actions after all of the finished machining processes have been performed. Heat is the first one to come to mind, but strain and vibration can also be a contributing factor.

We deal with this on a constant basis at my shop. When machining long shafts, you get a first hand view as to the amount of stress that can be induced into a piece of material through machining, and the amount that can be released. We are constantly having to straighten them throughout the entire marching steps, so that in the end, we end up with a long shaft that is truly straight.

But we rarely have to deal with an ID. 95 percent of the shafts we machine are solid. On occasion, we will have a shaft that has a hole through the center for a control rod or hydraulic system to operate a variable pitch Propeller system. We generally have these holes Trepanned and Reamed with the hope it will end up somewhere in the middle and be reasonably straight with it's self.

Very well stated. Doesn't take away much of the frustration of knowing that though. Would air gauging be able to see the hole wasn't straight before reaming begins if the test was done?

Happy New Year,

Pete

P>S>

I have watched a number of videos of Keith Fenner straightening shafts. Pretty interesting how he is able to straighten them and how little heat is required.

 

[jackie schmidt]

Very well stated. Doesn't take away much of the frustration of knowing that though. Would air gauging be able to see the hole wasn't straight before reaming begins if the test was done?

Happy New Year,

Pete

P>S>

I have watched a number of videos of Keith Fenner straightening shafts. Pretty interesting how he is able to straighten them and how little heat is required.

Pete, we straighten shafts at room temperature. The American Bureau of Shipping, (ABS), does not allow heat quench straightning.

We straighten shafts and bent rudder stocks up to 13 inches. Here are four pictures of a 9 inch diameter Rudder stock that we straightened. The first is with the straightening rig in place, getting ready. The next two are the actual straightening, the last, the finished job. Keep in mind, there are quite a few "hits" in between as you work the bend out.

The straightening rig has a 500 ton hydraulic ram. If you look behind the big Lathe, you see our largest one in it's cradle. It has a 750 ton hydraulic ram.

We designed and built these rigs ourselves. They are constructed from T-1 plate. We also have smaller ones for smaller applications, one at 150 and another at 300 tons.

We do this sort of thing on a regular basis.

http://benchrest.com/attachment.php?attachmentid=20529&stc=1&d=1514783143

http://benchrest.com/attachment.php?attachmentid=20530&stc=1&d=1514783256

http://benchrest.com/attachment.php?attachmentid=20531&stc=1&d=1514783344[/url}

 

[GeneT]

. Here are four pictures of a 9 inch diameter Rudder stock that we straightened. The first is with the straightening rig in place, getting ready. The next two are the actual straightening, the last, the finished job. Keep in mind, there are quite a few "hits" in between as you work the bend out.

That's really impressive. It would be hard to believe it's the same shaft if it weren't so distinctly 'charactered'. So, when you're chambering in that lathe, what do you do with the muzzle end? ;-)

GsT