Indexing a rifle barrel...

[butchlambert]

You still have a reading comprehension problem. I stated a reason for some barrels being straighter than others, bore wise and that is all. It could be 5 years apart and two barrels could be straight. . Go back and read my post. Now that we have skipped over that, how was the bore straightness measured in your barrel. Not saying that you are wrong, just how did you determine your measurements.

 

[savagedasher]

You still have a reading comprehension problem. I stated a reason for some barrels being straighter than others, bore wise and that is all. It could be 5 years apart and two barrels could be straight. . Go back and read my post. Now that we have skipped over that, how was the bore straightness measured in your barrel. Not saying that you are wrong, just how did you determine your measurements.

The barrels are chambered through the head stock in the lathe. And the run out is trued off a range rod that fits in the barrel with a bushing in front and the taper to the rear at the barrel and 4" back it runs true . So the center of is bore is true I the back. You must have spiders on both end of the lathe and
all are adjusted to get the alignment and not bend the barrel . Take the rod out and install in the front and that will give you the straightness.
The old method that still used put the barrel u to a light and look at the rings when you rotate the barrel if the rings don't move it is straight. Both barrels past the same test. Larry

 

[WayneShaw]

There is no question in my mind that the drilling of barrels have improved vastly in the past 10 to 15 years or so. Before then , it was common to see the spiral down the bore and some were significant. Now, that is rare. Most now are quite good.

There was one maker that had the most crooked bore you ever saw, but the barrels shot fantastic and won many matches.

 

[shortgrass]

I never have seen anything about the drilling process being changed that hasn't changed in years. Guess I have good luck. Larry

If you don't realized that tooling technology is advancing by leaps and bounds, you've got your head in the sand!

 

[gunsandgunsmithing]

Honing can and certainly does straighten a hole in a given context. Perhaps there is some misunderstanding or misinterpretation of what happens and of what is being said.

I've used Sunnen hones for align honing the main journals of an engine block. In a nutshell, what you do is take a few thou off of the bottom of all the main caps, creating an egg shapeed bore. Remember, the hole has to be undersize before honing to size. A small block chevy has 5 main caps..Lets say that we have one cap already perfectly sized, round, and centered to the correct centerline of the 5 journals..We'll put that cap in the middle. Now, we have a crooked bore, with the center cap being the only one that is to size and straight..where we want it. If we took a straight edge and held it against the bore surface of all 5 caps, there'd be a gap at the one that is finished. Does everyone agree that we now have a crooked bore?

Now, if we hone the others until they are all perfectly round with the middle cap, we have straightened the bore and corrected any misalignment of the bore. Coincidentally, core shift is the biggest reason this happens with cast iron engine blocks after going through many heating,cooling cycles, then unbolted, relieving the stresses being stored in the block.

If we can agree that we have straightened the bore of the main journals, we should now be able to agree that honing can and does straighten a bore..but it must start out undersized and hone to size. Straightening the hole is the result. This process really has nothing to do with the od of the caps or block, and so, has nothing to do with the od of a barrel, either. So, what Butch says is true relative to the bore not being centered with the od. But any crook, kink or curve in the bore, theoretically can be honed out...within reason, of course, and depending on how much under size the hole started out and how much it takes to both end up straight and to size. Hopefully, we can all agree as to how honing can and does straighten a hole in this context.

Now, as for the benefits of honing the bore...There are pro's and cons. First, too smooth of a finish doesn't reduce fouling..it makes it worse. It also matters as to how the barrel is to be rifled..be it cut or buttoned. To my knowledge, with cut rifling, the only down side would be the potential for more fouling IF not lapped well after rifling. Of course this is not the case with most premium barrels and it would only affect the top of the lands..that are already to size when the grooves are cut.

But on button rifled barrels, the force needed to push or pull a button through the bore of a finely honed bore is not less, but much, much higher. I can only assume this is due to not holding lube as well as a less "finished" bore before rifling. Not that it can't be done though..as others have mentioned a couple of barrel makers who are known to button rifle their barrels, also hone the bores before rifling. I believe that it only needs to be factored into what the pre rifling bore dimensions are relative to the finished button dimensions are. I view this much like the barrels that Savage produces, in which many of us are familiar with their infamous "railroad tracks with cross ties", appearance with a bore scope. I opine this as the result of marginal(to put it nicely) bore to button dimensions, in order to reduce wear, tear and stress on tooling as well as speed up production..by the button not fully ironing out the marks left from the drilling operation. Take that FWIW because it's a combination of reasoning and knowing just enough about the process to be dangerous. The pressure to push/pull the button through a smooth vs. less smooth drilled rifle barrel came straight from the mouth of the owner a barrel making company...along with numbers that I don't recall precisely..but it was like night and day, with no other differences other than finish of the drilled/honed hole prior to rifling. Then you have to figure how much the bore with change size during heat treat, too....and that number can change with the batch of steel and the time/temp for heat treat. There's a lot more that goes into making top quality barrels than meets the eye.---Mike Ezell

 

[savagedasher]

There is no question in my mind that the drilling of barrels have improved vastly in the past 10 to 15 years or so. Before then , it was common to see the spiral down the bore and some were significant. Now, that is rare. Most now are quite good.

There was one maker that had the most crooked bore you ever saw, but the barrels shot fantastic and won many matches.

If you don't realized that tooling technology is advancing by leaps and bounds, you've got your head in the sand!

I do but the drilling hasn't changed . They have added machine honeing . It looks like the the hone is guided on both ends. If the hone is long enough and guided It definitely will straighten the bore No Sand on this End
Larry

 

[savagedasher]

Honing can and certainly does straighten a hole in a given context. Perhaps there is some misunderstanding or misinterpretation of what happens and of what is being said.

I've used Sunnen hones for align honing the main journals of an engine block. In a nutshell, what you do is take a few thou off of the bottom of all the main caps, creating an egg shapeed bore. Remember, the hole has to be undersize before honing to size. A small block chevy has 5 main caps..Lets say that we have one cap already perfectly sized, round, and centered to the correct centerline of the 5 journals..We'll put that cap in the middle. Now, we have a crooked bore, with the center cap being the only one that is to size and straight..where we want it. If we took a straight edge and held it against the bore surface of all 5 caps, there'd be a gap at the one that is finished. Does everyone agree that we now have a crooked bore?

Now, if we hone the others until they are all perfectly round with the middle cap, we have straightened the bore and corrected any misalignment of the bore. Coincidentally, core shift is the biggest reason this happens with cast iron engine blocks after going through many heating,cooling cycles, then unbolted, relieving the stresses being stored in the block.

If we can agree that we have straightened the bore of the main journals, we should now be able to agree that honing can and does straighten a bore..but it must start out undersized and hone to size. Straightening the hole is the result. This process really has nothing to do with the od of the caps or block, and so, has nothing to do with the od of a barrel, either. So, what Butch says is true relative to the bore not being centered with the od. But any crook, kink or curve in the bore, theoretically can be honed out...within reason, of course, and depending on how much under size the hole started out and how much it takes to both end up straight and to size. Hopefully, we can all agree as to how honing can and does straighten a hole in this context.

Now, as for the benefits of honing the bore...There are pro's and cons. First, too smooth of a finish doesn't reduce fouling..it makes it worse. It also matters as to how the barrel is to be rifled..be it cut or buttoned. To my knowledge, with cut rifling, the only down side would be the potential for more fouling IF not lapped well after rifling. Of course this is not the case with most premium barrels and it would only affect the top of the lands..that are already to size when the grooves are cut.

But on button rifled barrels, the force needed to push or pull a button through the bore of a finely honed bore is not less, but much, much higher. I can only assume this is due to not holding lube as well as a less "finished" bore before rifling. Not that it can't be done though..as others have mentioned a couple of barrel makers who are known to button rifle their barrels, also hone the bores before rifling. I believe that it only needs to be factored into what the pre rifling bore dimensions are relative to the finished button dimensions are. I view this much like the barrels that Savage produces, in which many of us are familiar with their infamous "railroad tracks with cross ties", appearance with a bore scope. I opine this as the result of marginal(to put it nicely) bore to button dimensions, in order to reduce wear, tear and stress on tooling as well as speed up production..by the button not fully ironing out the marks left from the drilling operation. Take that FWIW because it's a combination of reasoning and knowing just enough about the process to be dangerous. The pressure to push/pull the button through a smooth vs. less smooth drilled rifle barrel came straight from the mouth of the owner a barrel making company...along with numbers that I don't recall precisely..but it was like night and day, with no other differences other than finish of the drilled/honed hole prior to rifling. Then you have to figure how much the bore with change size during heat treat, too....and that number can change with the batch of steel and the time/temp for heat treat. There's a lot more that goes into making top quality barrels than meets the eye.---Mike Ezell

Mike Is your head in the Sand?Larry

 

[shortgrass]

I do but the drilling hasn't changed . They have added machine honeing . It looks like the the hone is guided on both ends. If the hone is long enough and guided It definitely will straighten the bore No Sand on this End
Larry

ya',,, lots of sand! You've got too much internet traing and not enough practical experience.......

 

[savagedasher]

I have not seen any correlation between bore straightness and grouping ability of a barrel. I do only indicate the end I am working on and time the bore. No way a hone is straightening a rifle bore. The hone is not rigid enough. All its doing in a small hole is making the hole round and evening out the diameter. In the engine machine shop I was taught to fix any alignment issues by boring, then hone to size. Those hones do have enough rigidity to straighten a bore though.

Bartliens have been the straightest barrels I have chambered. Does that mean they shoot best? Nope, I'd still take a Krieger or Brux.

ya',,, lots of sand! You've got too much internet traing and not enough practical experience.......

ya',,, lots of sand! You've got too much internet traing and not enough practical experience.......

Only about 60 year worth . Started In machine shop in 1959 . And you?
Larry

 

[gunsandgunsmithing]

I have not seen any correlation between bore straightness and grouping ability of a barrel. I do only indicate the end I am working on and time the bore. No way a hone is straightening a rifle bore. The hone is not rigid enough. All its doing in a small hole is making the hole round and evening out the diameter. In the engine machine shop I was taught to fix any alignment issues by boring, then hone to size. Those hones do have enough rigidity to straighten a bore though.

Bartliens have been the straightest barrels I have chambered. Does that mean they shoot best? Nope, I'd still take a Krieger or Brux.

Alex, I'm surprised you feel that way, if you've ever actually used one. They in fact work on the very principle that disproves your logic. I do agree that if the alignment is out far enough, boring first is the way to go. IIRC, the threshold was around .003" of misalignment before align boring was to be used before align honing. As to the hone mandrel being too flexible, it's supported. The stone/s protrude from the mandrel progessively, which works much like a pilot, and the stones are relatively long to span a wider area of the bore. In the case of an engine block, there is several inches between main journals. Not so in a rifle bore, so the mandrel is much better supported inside the bore. Perhaps there is still a misinterpretation of how they work and what they can and can't do..and what different people envision.

New and better equipment pretty much makes it a moot point though, as the new equipment is capable of drilling longer and straighter than the old. Perhaps honing was perceived as a way of getting by without buying state of the art drilling equipment...I don't know. I've said my piece. You guys can hash it out if you want to. I have no plans for making barrels and will leave what it takes to make them, to the barrel makers.

 

[savagedasher]

Learned from a guy who built all the race engines at the Marina on lake St.clair off Jefferson ave. I was in my early 20s. But what does that have to do with my post?

Learned from a guy who built all the race engines at the Marina on lake St.clair off Jefferson ave. I was in my early 20s. But what does that have to do with my post?

Sorry Alex It was ment for Shortgrass .
Not much has ben said about timing a barrel I said the last two was so straight the didn't need to be timed. Larry

 

[Alex Wheeler]

Mike, I dont disagree that you can hone a main bore on a block straight. The bar has the rigidity to do so. In a barrel bore the hone is too small a diameter to be rigid enough to be able to straighten a 30" long hole. Thats just how I see it.

 

[gunsandgunsmithing]

Sorry Alex It was ment for Shortgrass .
Not much has ben said about timing a barrel I said the last two was so straight the didn't need to be timed. Larry

As for indexing...I'll do it if the customer wants it done, but I don't index my own and have tried many, both ways. Tuners negate whatever benefit there MIGHT or MIGHT NOT be, as they bias the barrel more so on the vertical plane by simply adding mass to the end of the beam...gravity and leverage.

 

[savagedasher]

As for indexing...I'll do it if the customer wants it done, but I don't index my own and have tried many, both ways. Tuners negate whatever benefit there MIGHT or MIGHT NOT be, as they bias the barrel more so on the vertical plane by simply adding mass to the end of the beam...gravity and leverage.

 

[savagedasher]

[/QUOTE
Mike
I shoot a Savage with a tuner and I need any advantage I can get Larry

 

[gunsandgunsmithing]

Mike, I dont disagree that you can hone a main bore on a block straight. The bar has the rigidity to do so. In a barrel bore the hone is too small a diameter to be rigid enough to be able to straighten a 30" long hole. That's just how I see it.

I'll say this and let you all sort it out...The stone is directly opposed by the other side of the barrel bore. You can put a lot of pressure on the stones. If you're envisioning a long, gradual curvature(longer than the stone) then I can see your logic...but that's the kind of crookedness I'd guess to be one of the least of our worries. I'm more concerned with fairly fast crooks in the throat area, or just in front of it, that affect the reamer and pilot. We've all seen barrels that are quite "crooked" shoot lights out. I just don't want it where it affects the chambering job. A hard or soft spot in the steel can do what I'm talking about, pretty quickly, as I'm told by barrel makers, and many of us have seen, even drilling something far less critical..on a drill press!! Try drilling a steel pin or bolt out of a piece of aluminum, for example. LOL!--Mike

 

[Alex Wheeler]

I'll say this and let you all sort it out...The stone is directly opposed by the other side of the barrel bore. You can put a lot of pressure on the stones. If you're envisioning a long, gradual curvature(longer than the stone) then I can see your logic...but that's the kind of crookedness I'd guess to be one of the least of our worries. I'm more concerned with fairly fast crooks in the throat area, or just in front of it, that affect the reamer and pilot. We've all seen barrels that are quite "crooked" shoot lights out. I just don't want it where it affects the chambering job. A hard or soft spot in the steel can do what I'm talking about, pretty quickly, as I'm told by barrel makers, and many of us have seen, even drilling something far less critical..on a drill press!! Try drilling a steel pin or bolt out of a piece of aluminum, for example. LOL!--Mike

Thats exactly what I was talking about. Straightening the entire bore.

 

[gunsandgunsmithing]

Thats exactly what I was talking about. Straightening the entire bore.

Yes, see..I just don't consider that an issue. It's well accepted that they shoot just as well as one without the curve and it doesn't cause issues with chambering. I'm much more concerned with the bore being dimensionally uniform and not having any faster crooks that do cause chambering problems. But again, I think we are on the cusp of seeing new and better drilling equipment with which both types of crooks/curves are greatly improved. From what I've seen, much straighter deep hole drilling technology is available. I think it's a matter of time before most makers move to it. We're already blessed with several very good barrel makers but things look like they may get even better in the near future. I'm most impressed with what I've seen so far and have another on the way.

 

[Alex Wheeler]

Yes, see..I just don't consider that an issue. It's well accepted that they shoot just as well as one without the curve and it doesn't cause issues with chambering. I'm much more concerned with the bore being dimensionally uniform and not having any faster crooks that do cause chambering problems. But again, I think we are on the cusp of seeing new and better drilling equipment with which both types of crooks/curves are greatly improved. From what I've seen, much straighter deep hole drilling technology is available. I think it's a matter of time before most makers move to it. We're already blessed with several very good barrel makers but things look like they may get even better in the near future. I'm most impressed with what I've seen so far and have another on the way.

I agree.

 

[shortgrass]

Only about 60 year worth . Started In machine shop in 1959 . And you?
Larry

Aww shucks, I've only been machining since '74. Mostly in job shop settings but a few years in a bearing plant with several years in a plant where we made control valves for the Navys' nuculear power plants. What did you do,,, work in the same shop doing everything the same ol' way for all those years? In the past 10-15 years, since you've been retired , tooling has made some of the greatest advances I've seen in my working life. And I've had my hands on it, working with some of that "new" technology. While you're sitting around tapping on those computer keys all day, as your posts show, I'm still makin'chips and getting dirt under my finger nails taking advantage of that new tooling technology and being exposed to more, all the time. Drilling has changed, turning has changed, you're behind the curve. That hone, no matter what you think, is not going to "straighten out the hole" in the manner you are proposing. It all starts with the initial drilled hole and the quality of the material being drilled. Both of those (tooling and material, as long as it's the premium stuff, like rifle barrels are made of) have made tremendous advances in the past 10yrs (since you've been retired).