Barrel Indexing,,

[Gene Beggs]

,,is something I have studied for years and I'm happy to learn that others are experimenting with it as well. Most recently, Gordy Gritters addresses this in his DVD on chambering.

For some time I have understood why, from a vibration standpoint, it is important to install a barrel with the natural curvature oriented in the verticle plane but have had some question about whether the curve should be pointed up or down. Gordy Gritters, in his excellent video on chambering, says he prefers the curve be pointed up at twelve o'clock, and if I understand correctly, he feels this is advantageous for long range shooting from a sight/elevation/POI standpoint. Being a so-called 'point blank' shooter, (100, 200 & 300) I am not concerned with POI vs., sighting plane, but only from a tuning/vibration standpoint.

Mike Ross, in his excellent article on indexing says he invariably gets best grouping with the curve placed at six o'clock. Since reading his article, I have been placing the curve at six o'clock and unless I discover something that suggests otherwise, that will be my standard procedure. I think it is important.

I was very surprised when I read Bill Calfee's article in PS on barrel indexing because his findings were diametrically opposed to those of Mike Ross and myself. Billllllllll,,,,,, now you wouldn't be trying to hide something from us; would you? Huhhhhh?? Sure you would, you sly devil you. Come on, tell the truth, barrel indexing is VERY important; isn't it??

Let's see now,,, I better hunker down behind this mesquite brush and stay out of sight for a while.

Later,

GeneBeggs

 

[Chisolm]

Gene
Here is a copy of my post on barrel indexing from your deleted thread. Thank you Larry for quoting me in your reply, so I have a copy instead of needing to retype it.

For my tension tube experiment I also wanted to have the bore pointed
up in the vertical plane. To find which way the bore pointed at the
muzzle I set up the barrel just like Gordy does to chamber except on the
muzzle end. Then I placed a witness mark on the chamber end to indicate
the point that should be clocked down. Then I re-indicated the barrel so
the bore and the chamber are running true and threaded the muzzle for
the tube nut. Now I am waiting on the stock before I chamber and thread
the shank, since the action is still in use until I get the new stock.
I am also thinking because of the tube it would be better to indicate
the bore centered at both ends when cutting the chamber as opposed to
how Gordy does it.
I just thought I would throw that out there for others to look at and
maybe tell me why this method will not work to index the barrel.


I also obviously believe there is something to be gained by indexing the barrel. Upon reading Bill’s article on barrel indexing I just assumed that because of the lower pressures with the rimfire that it must be less affected by how the barrel is indexed.
Wonder what Bill thinks.

James

 

[jackie schmidt]

Gene

The one point of contention I would have with this is there is no such thing as the "natural curvature" of a barrel. The vast majority of barrels are simply drilled withy crooked spots caused by the gun drill wandering off at spots. These crooked spots might run at random with each other. The piece of steel is still just as straight as it was before it was drilled.........jackie

 

[J. Valentine]

The one point of contention I would have with this is there is no such thing as the "natural curvature" of a barrel. The vast majority of barrels are simply drilled withy crooked spots caused by the gun drill wandering off at spots. These crooked spots might run at random with each other. The piece of steel is still just as straight as it was before it was drilled.........jackie

Thanks Jackie for asking, I was not game , It is very confussing to me , how do I find this natural curve that may only be in part of the bore.

 

[Gene Beggs]

Mornin' Jackie,,

The one point of contention I would have with this is there is no such thing as the "natural curvature" of a barrel. The vast majority of barrels are simply drilled with crooked spots caused by the gun drill wandering off at spots. These crooked spots might run at random with each other. The piece of steel is still just as straight as it was before it was drilled.........jackie

Jackie, your point of contention is one I hear often when discussing this barrel indexing thing with others. Your objections notwithstanding, I still believe the vast majority of barrels do have some degree of natural curvature, which is likely caused by heat treating.

Years ago, Harold Broughton taught me how to visually check for curvature by turning the barrel in the lathe while sighting down the bore at a live center. It's amazing how effective this method is.

The quality of barrels being produced today by the major manufacturers is incredible; I don't believe it would be humanly possible to do better, but none are perfect.

When I first started experimenting with indexing, I made a balance fixture using ball bearings and bore pins. I would place a new barrel in the fixture, give it a spin, and the heavy side would soon come to rest at the bottom. I no longer use this method.

Now, I detect the natural droop with a dial indicator at the muzzle, adjusting the tenon shoulder to place this droop at the six o'clock position on the receiver. This is probably a best guess and a good starting point, but you never know what you have until you start shooting the barrel.

When the rifle is out of tune, it will print a verticle signature on the target. If this pattern is perfectly verticle, the barrel is installed correct and is vibrating only in the verticle plane. If the group leans to one side or the other, the barrel is not properly indexed. If the barrel prints from one to seven o'clock, this can be corrected by reindexing clockwise thirty degrees.

Later,

Gene Beggs

 

[Edwin D]

Gene,

your opinion please.

Do "GUNSMITHS" know this secret, AND use it?

 

[Gene Beggs]

Gene,

your opinion please.

Do "GUNSMITHS" know this secret, AND use it?

Ed, you can bet your boots Bill Calfee knows about it, but if the others do as well, they sure aren't saying much about it; are they?

Later,

Gene Beggs

 

[HuskerP7M8]

I first became interested in barrel indexing a few years ago and started searching for threads and posts across multiple forums. I honestly don’t know why I’ve become so fascinated or obsessed with the subject, but I have.

Many of you, perhaps even the majority of you probably feel like it has already been dealt with to your satisfaction and it simply isn’t worthwhile to hash it all out again.
Even on this forum alone, there are probably a couple of dozen threads and maybe a hundred posts or more….I haven’t tried to count them all.

I want to try and explain why “I” think this discussion is important enough to once again be revisited.

In the last few months, I realized that if I were to compile two lists with the first one being comprised of those who had actual experience in testing and valid statistical results both pro and con…..the pro side of that list would be longer.
The second list would be comprised of those who had “opinions” only and that list was weighted to the con side.

With the disparity in these two lists and a presumption of results being more important than opinions, shouldn’t an attempt be made to convince those with opinions only?

Even though I’m obviously biased in favor of barrel indexing, I will be just as happy being proved wrong as right. After all, our ultimate goal is the advancement of accuracy. I have to admit I might feel a little sheepish and wish I’d kept my opinions to myself, but ultimately that conduct is worse than being wrong and saying nothing.

Landy

 

[Hal]

Couldn't the barrel indexing theory be tested with a rail gun set up. With the barrel and action being rotated at a 12 o'clock, 3 o'clock, 6 o'clock, 9 o'clock index and a group fired at each position and a combination group being fired to include a shot from each position?

Just like Pope and Mann? did a 100 years ago.

Hal

 

[wolf gray]

Mesquite Bushes

Gene,
I've seen the mesquite bushes in Odessa, you'll need 2.

Best,

Dan Batko

 

[Gene Beggs]

Couldn't the barrel indexing theory be tested with a rail gun set up. With the barrel and action being rotated at a 12 o'clock, 3 o'clock, 6 o'clock, 9 o'clock index and a group fired at each position and a combination group being fired to include a shot from each position?

Just like Pope and Mann? did a 100 years ago.

Hal

Yes Hal, Mike Ross used a railgun type setup to conduct his tests; I have done all my testing with a bag gun. Results were the same. I do not feel further testing is necessary. My experience with several different bag guns have convinced me; it's a fact, not theory.

So Pope and Mann did all this 100 years ago? I'm not surprised. Just when we newbies come up with something we get all excited and think we were the first to think of such a thing only to discover that so and so did that long ago. So soon we forget; eh?

Later,

Gene Beggs

 

[J. Valentine]

Gene , when I look down the bore at the live center , what will I see for a bent barrel and a straight barrel and how will I relate that to an index direction ?
Did it today and I cant detect any wobble relevant to the live center point .
Is that the way to do it?

 

[Charles E]

Ed, you can bet your boots Bill Calfee knows about it, but if the others do as well, they sure aren't saying much about it; are they?

Of course Calfee knows about it, since he wrote a two-part article on his tests in Precision Shootong, where he concluded it was of no use for rimfire barrels.

The problem with any of these "new" (actually, recently rediscovered) procedures is that sometimes they work, and sometimes they don't. Until we know why they work, we don't have much of a handle on where to put our efforts, or even how to best implement them.

I have some experience with making and using tensioning tubes. I cannot tell you why they work, and I can't even give you a recipe for constructing a tube system that will work every time. So, I can't answer the question as to whether a tensioning tube makes a poor to average barrel considerably better but has a lesser effect on a good barrel, or has an equal effect on all barrels. The reason is that we can't always get consistent results, and until we know how to make a tensioning system that works the same every time, we don't know what are the build problems and what are the barrel problems. Then too, with individuals working on these things, the sample size is obviously going to remain pretty small.

The same with tuners, & I'd say the same with barrel indexing.

There are so many variables in shooting very small groups, from bullets & barrels & bedding & actions & stocks & barrel blocks, to (if you are outside) "conditions," that as you get ever-closer to the .0XX agg, it is very hard to say just what's at play with any given test an individual can perform.

Then there is the cost factor: remember the thread on floating bolt heads? I believe Jerry Stiller said that yes, they did seem to improve things just a bit, but not enough to warrant all the extra machining time necessary to make them.

So, suppose that indexing barrels helps a "bad" barrel" but not a "good" barrel? What are we to do? Index all barrels since we don't know ahead of time which are "good" and which are "bad?" And, as seems likely, suppose an indexed "bad" barrel shows improvement, but still does not come up to the performance level of a "good" barrel. Where are we then? Better would be to discover why indexing works, if it does, so we could then consider the merits of having all barrels made to minimize the whatever "bad" effect indexing is improving.

But of course, this would likely increase the manufacturing cost, & we'd then have to decide if it is worth it.

So once again, the most important information we could get is "why." And for competition, the importance of that is second to learning how to shoot in adverse conditions.

FWIW

 

[Roy in NC]

Good post Charles

I guess that's why I get so caught up in the WHY dsicussions on tuners. Most folks seems to have the "if it works don't ask why" attitude, but I feel that you cannot determine the best way to use or improve on a concept if the WHY is not understood.

FWIW,

Roy

 

[Pete Wass]

Just from what I have read here

Indexing would seem an elementry part of fitting a barrel. It shouldn't take a long time to find the index point or to fit the shoulder to the action face. Why wouldn't it become a standard practice? P

 

[Vibe]

Yep. "Why" is very important, particularly when attempting to pass on the information. As is a common base of terminology to describe the "Why".

 

[Don]

Of course Calfee knows about it, since he wrote a two-part article on his tests in Precision Shootong, where he concluded it was of no use for rimfire barrels.

The problem with any of these "new" (actually, recently rediscovered) procedures is that sometimes they work, and sometimes they don't. Until we know why they work, we don't have much of a handle on where to put our efforts, or even how to best implement them.

I have some experience with making and using tensioning tubes. I cannot tell you why they work, and I can't even give you a recipe for constructing a tube system that will work every time. So, I can't answer the question as to whether a tensioning tube makes a poor to average barrel considerably better but has a lesser effect on a good barrel, or has an equal effect on all barrels. The reason is that we can't always get consistent results, and until we know how to make a tensioning system that works the same every time, we don't know what are the build problems and what are the barrel problems. Then too, with individuals working on these things, the sample size is obviously going to remain pretty small.

The same with tuners, & I'd say the same with barrel indexing.

There are so many variables in shooting very small groups, from bullets & barrels & bedding & actions & stocks & barrel blocks, to (if you are outside) "conditions," that as you get ever-closer to the .0XX agg, it is very hard to say just what's at play with any given test an individual can perform.

Then there is the cost factor: remember the thread on floating bolt heads? I believe Jerry Stiller said that yes, they did seem to improve things just a bit, but not enough to warrant all the extra machining time necessary to make them.

So, suppose that indexing barrels helps a "bad" barrel" but not a "good" barrel? What are we to do? Index all barrels since we don't know ahead of time which are "good" and which are "bad?" And, as seems likely, suppose an indexed "bad" barrel shows improvement, but still does not come up to the performance level of a "good" barrel. Where are we then? Better would be to discover why indexing works, if it does, so we could then consider the merits of having all barrels made to minimize the whatever "bad" effect indexing is improving.

But of course, this would likely increase the manufacturing cost, & we'd then have to decide if it is worth it.

So once again, the most important information we could get is "why." And for competition, the importance of that is second to learning how to shoot in adverse conditions.

FWIW

Hi Charles,

Here is my last attempt at indexing a barrel in order to improve a slight leakage problem on a LV barrel, that looked like it might be competitive if the problem could be fixed............see targets 1-4, 100 yards, 5 shot groups, with leakage problem of best load 6PPC, 30.0 gr N133, 66gr FB.

Took the barrel/action put it in railgun adapter, fired 3 shot groups, 3-6-9-12 oclock positions (relative to top of action, barrel curvature had not been predetermined while in lathe), by spinning barrel/action in railgun adapter barrel block, all using the same aimpoint= 7 oclock position of target#5. 9 oclock impacted highest, 3 oclock lowest, and 6,12 oclock impacted together in the middle of the high and low, leading me to believe the barrel curve was probably in the 9 oclock position relative to the top of the action. Surprisingly little impact overall change with different index positions, no more than 1 inch verticle change.

9 oclock position seemed to fire the smallest 3 shot group so I followed this up with (2) more 5 shot groups, targets 6 and 7, .210 and .230 moa respectively, both slashing from 1 to 7 oclock, and no better improvement over targets 1-4.

So another single indexing experiment with no clear cut improvement or conclusion, others I have performed have also generally resulted in the same outcome.................Don

 

[Kathy]

Friend Don:

Friend Don:

A suggestion, for what it's worth, about your barrel with "a slight leakage problem"....

Clean the bore, then insert a slug in the breech, then push it to the muzzle, slowly....pay attention to what you feel just as the slug exits the crown...

Insert another slug, push it slowly to the crown, but this time, don't push the slug out of the bore......carefully push it so it protrudes through the crown....then take your finger and push the slug back into the bore.....

When you do this, if you want to fool with it, get back on this thread and describe how the slug felt when you pushed it back in the bore with your finger........did it push easy? Did it push hard? could you push it back at all?

If and when you do this test, and I read your findings, I'll give you something else to check......save the slugs......

Oh, Don, 22 rimfire bullets can be bumped up to either 22 centerfire or 6MM...

Don, one other thing: If you decide to run this little test, would you consider starting a new thread with your results......this way we won't be taking up folks time here on this "barrel indexing" thread......

Your friend, Bill Calfee

 

[Don]

Friend Don:

A suggestion, for what it's worth, about your barrel with "a slight leakage problem"....

Clean the bore, then insert a slug in the breech, then push it to the muzzle, slowly....pay attention to what you feel just as the slug exits the crown...

Insert another slug, push it slowly to the crown, but this time, don't push the slug out of the bore......carefully push it so it protrudes through the crown....then take your finger and push the slug back into the bore.....

When you do this, if you want to fool with it, get back on this thread and describe how the slug felt when you pushed it back in the bore with your finger........did it push easy? Did it push hard? could you push it back at all?

If and when you do this test, and I read your findings, I'll give you something else to check......save the slugs......

Oh, Don, 22 rimfire bullets can be bumped up to either 22 centerfire or 6MM...

Don, one other thing: If you decide to run this little test, would you consider starting a new thread with your results......this way we won't be taking up folks time here on this "barrel indexing" thread......

Your friend, Bill Calfee

Hi Bill,

That was a very poor use of terms by myself in saying "a slight leakage problem"...............I meant to indicate that this particular barrel seemed capable of shooting competitive, tight 5 shot groups, in the .150 moa 100 yard range, but would always "leak" or "wonder" enough shots to open groups up into the mid .2s, usually in a slanting and slashing type pattern.

I did not mean to suggest that the barrel "leaked" from gas blow-by, as I can now see that it was probably interpreted that way. In fact, according to my records, this particular Krieger barrel, when sluggged, showed a very consistent bore with a slight taper from chamber to muzzle, but not so much so to create muzzle coppering, something that rimfire barrels usually dont have to worry about.

After performing this and other indexing tests on barrels that would not quite shoot competitively, by rotating the barrelled/actions in a railgun barrel block adapter fixture, Ive come away with the same kind of feeling/conclusion that you described in your Sept/October 2007 PS articles about barrel indexing.

Even so, I will probably periodically index other barrels that show certain characteristics, to see if indexing can achieve some type of improvement.........................Don

 

[pacecil]

The problem with testing a barrel to see how bore-out-of-straightness might affect it is that you really have no way to measure the bore straightness. After the test you don't know how to relate the results to the curvature. You might have been testing a barrel that was straight, or it might have had a curve in one plane, or it might be a barrel with curvature in multiple planes. I thought Ross decided the barrels performed best when curvature was toward 12,00 oclock, rather than 6 oclock. I might be wrong on this, but the point is he didn't know which direction the curvature took- or if it took multiple directions.

Barrels can be set up and rotated and an indication of general shape of the bore made but no actual measurement can be made. I've questioned barrel makers and most of them just believe their barrel are within .005 of being perfectly straight, but they really don't know. Deviation of .005 in 24" is probably a good figure to apply to most deep hole drilling but here again this depends on tooling and steel hardness and composition consistency.

I've looked into laser alignment tools to measure bore deviation with but could not find anyone to make a small enough target to put through a 22 cal. barrel. (The target is what the beam strikes and on which the deviation would be measured.)

This may be one of those things you just have to test and see if a barrel shoots better at one position and if it does try and install it at that position. Until you can measure the barrel you may never know why it does what it does.