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Gene Beggs
01-13-2008, 03:30 PM
Guys, many of us have been studying and experimenting with this barrel vibration/tuner thing for several years. Much progress has been made, thanks to Bill Calfee, Harold Vaughn, Varmint Al, and those who participated in discussions here on BR Central.

Not so long ago, I had very little understanding of barrel vibration, and no one was more skeptical of tuners than I was. But, with time, patience and the help of those much smarter, the big picture finally came into focus. I'm not saying I know it all, but I assure you, I understand perfectly what we as shooters must know in order to take advantage of the latest in tuner technology.

NBRSA permits, and I'm sure IBS will soon follow, the use of tuners in sanctioned competition. Beginning in 2007, NBRSA also permits adjustment at the bench, so long as the bolt is removed and the shooter remains seated. This is a tremendous advantage for those who know how to use a tuner. Regardless of location, atmospheric conditions, phase of the moon or whatever, the powder charge need never be changed; all tuning can now be done with the tuner.

I'm sure there are those who are thinking, "SAY WHAT? Come on Beggs,, you've got to be kidding." :rolleyes:

I'm just as serious as a heart attack! When you discover how easy it is to keep a rifle in tune with a tuner you will slap your forehead and say, "Damn, I can't believe it; you mean that's all there is to it?"

Yep, that's all there is to it, the big hairy monster we have been battling for years has finally been conquered. Listen up. ;)

Some of you are probably wondering, "Beggs, if this thing is so good, why are you telling everyone in the world about it?"

Good question. My answer?

If I was hell bent on winning, and it meant that much to me, I would do my best to keep this a secret, but those who know me well understand, I am first and foremost an experimenter, writer, and teacher. My greatest satisfaction comes from developing and introducing new, inovative, products and services.

When I began experimenting with tuners in the tunnel a couple of years ago, I quickly realized; this was the answer to keeping a rifle in tune. What I did not understand was exactly how they worked. I was led to believe that only the weight added beyond the muzzle affected tune. I have since discovered this is not the case and the discovery has led to developement of a simple, inexpensive, but very effective tuner that will soon be available to everyone. The CNC shop is writing the program at this time and will begin production right away.

The tuner consists of only two identical parts. Two precision machined stainless steel collars thread onto the muzzle. They are drilled radially in four places and once positioned, tighten against each other with two small 'Tommy Bars' making adjustment at the bench easy, simple and fast.

Installation requires threading the muzzle and turning the last inch to .8490. Why? This perfectly fits a two liter soft drink bottle, which contains the spray and patches from cleaning. :D :D

FAQ's

1. When will these tuners be available? Soon.

2. How much will they cost? Yet to be determined.

3. How much weight penalty is involved? Three ounces, total.

4. How does it work? By changing the vibration frequency of the barrel, which enables one to adjust muzzle stop to coincide with bullet exit. Think of the tuner as a focusing ring. If you monitor density altitude and can read a clock, you can keep your rifle perfectly in tune throughout the day and never change the load.

5. Do you have a patent on this thing? No, this has been done before in one way or another and besides; I don't believe in patents. A patent is useless unless you are willing to defend it in court, and I am not. I prefer to share with others. If someone thinks they can do a better job at a lower price, I say, "More power to 'em."

6. Browning has a patent on their BOSS system; are you concerned about infringing on their patent? No, the BOSS is an attachment that screws on and extends beyond the muzzle, much like a muzzle brake. My collars are positioned back on the barrel approximately one inch behind the muzzle. Two different things.

7. Are you concerned that someone else will try to patent your idea? No,,, I have already told you about it and it's been seen in public many times. No one can patent it.

8. Why should I buy these collars from you? Could I not just thread a couple of cheap hex nuts on the muzzle and tighten 'em with a pipe wrench? :cool: Yeah, you could do that, but how much would they weigh? How far would you have to move them and in which direction as density altitude changes? And how much would the point of impact change after an adjustment? I've spent years and many thousands of dollars working all this out; I KNOW the answers to these questions. Also, point of impact does not change after an adjustment with my tuners. They are precision made on CNC equipment, balanced perfectly and all weigh exactly the same. That's very important.

9. Can I install the tuner or must it be installed by a gunsmith? Unless you are familiar with precision threading on a manual lathe, it would be best to have your gunsmith do the installation.

10. So, if I want one of these things, when and where will they be available? Stay tuned to BR Central, I'll advise you when the first batch is finished.


Guys, 2008 is going to be an exciting year! Best of luck to you.

Later,,

Gene Beggs

Dave Short
01-13-2008, 03:59 PM
Gene,

Pertaining to FAQ #4, Here is question #11: Are you saying that you move the rings a predetermined amount in a given direction for incermental changes in density altitude? Or is each combination different because of the type and charge of powder being used, primer, bullet, barrel length, contour, and "personality"......or, in short, the factors that can and do effect the tune and accuracy of any given combination?

Interesting stuff...............
-Dave-:)

Doug Rumbaugh
01-13-2008, 04:08 PM
I have a 6.5 WSSM 1K BR rifle and a load that gives me unbelievable velocity spreads for long range (< 5 fps) but the groups are big, say .75" @ 100 yards. Other loads with a different powder give me small groups .25" @ 100 yards in good conditions but the velocity spreads are too large (25 fps). At 1000 yards, both give similar results. If I could tune the rifle to the low velocity spread load, I could substantially reduce my groups at long range.

Would this device be applicable in this case?

Don
01-13-2008, 04:20 PM
Guys, many of us have been studying and experimenting with this barrel vibration/tuner thing for several years. Much progress has been made, thanks to Bill Calfee, Harold Vaughn, Varmint Al, and those who participated in discussions here on BR Central.

Not so long ago, I had very little understanding of barrel vibration, and no one was more skeptical of tuners than I was. But, with time, patience and the help of those much smarter, the big picture finally came into focus. I'm not saying I know it all, but I assure you, I understand perfectly what we as shooters must know in order to take advantage of the latest in tuner technology.

NBRSA permits, and I'm sure IBS will soon follow, the use of tuners in sanctioned competition. Beginning in 2007, NBRSA also permits adjustment at the bench, so long as the bolt is removed and the shooter remains seated. This is a tremendous advantage for those who know how to use a tuner. Regardless of location, atmospheric conditions, phase of the moon or whatever, the powder charge need never be changed; all tuning can now be done with the tuner.

I'm sure there are those who are thinking, "SAY WHAT? Come on Beggs,, you've got to be kidding." :rolleyes:

I'm just as serious as a heart attack! When you discover how easy it is to keep a rifle in tune with a tuner you will slap your forehead and say, "Damn, I can't believe it; you mean that's all there is to it?"

Yep, that's all there is to it, the big hairy monster we have been battling for years has finally been conquered. Listen up. ;)

Some of you are probably wondering, "Beggs, if this thing is so good, why are you telling everyone in the world about it?"

Good question. My answer?

If I was hell bent on winning, and it meant that much to me, I would do my best to keep this a secret, but those who know me well understand, I am first and foremost an experimenter, writer, and teacher. My greatest satisfaction comes from developing and introducing new, inovative, products and services.

When I began experimenting with tuners in the tunnel a couple of years ago, I quickly realized; this was the answer to keeping a rifle in tune. What I did not understand was exactly how they worked. I was led to believe that only the weight added beyond the muzzle affected tune. I have since discovered this is not the case and the discovery has led to developement of a simple, inexpensive, but very effective tuner that will soon be available to everyone. The CNC shop is writing the program at this time and will begin production right away.

The tuner consists of only two identical parts. Two precision machined stainless steel collars thread onto the muzzle. They are drilled radially in four places and once positioned, tighten against each other with two small 'Tommy Bars' making adjustment at the bench easy, simple and fast.

Installation requires threading the muzzle and turning the last inch to .8490. Why? This perfectly fits a two liter soft drink bottle, which contains the spray and patches from cleaning. :D :D

FAQ's

1. When will these tuners be available? Soon.

2. How much will they cost? Yet to be determined.

3. How much weight penalty is involved? Three ounces, total.

4. How does it work? By changing the vibration frequency of the barrel, which enables one to adjust muzzle stop to coincide with bullet exit. Think of the tuner as a focusing ring. If you monitor density altitude and can read a clock, you can keep your rifle perfectly in tune throughout the day and never change the load.

5. Do you have a patent on this thing? No, this has been done before in one way or another and besides; I don't believe in patents. A patent is useless unless you are willing to defend it in court, and I am not. I prefer to share with others. If someone thinks they can do a better job at a lower price, I say, "More power to 'em."

6. Browning has a patent on their BOSS system; are you concerned about infringing on their patent? No, the BOSS is an attachment that screws on and extends beyond the muzzle, much like a muzzle brake. My collars are positioned back on the barrel approximately one inch behind the muzzle. Two different things.

7. Are you concerned that someone else will try to patent your idea? No,,, I have already told you about it and it's been seen in public many times. No one can patent it.

8. Why should I buy these collars from you? Could I not just thread a couple of cheap hex nuts on the muzzle and tighten 'em with a pipe wrench? :cool: Yeah, you could do that, but how much would they weigh? How far would you have to move them and in which direction as density altitude changes? And how much would the point of impact change after an adjustment? I've spent years and many thousands of dollars working all this out; I KNOW the answers to these questions. Also, point of impact does not change after an adjustment with my tuners. They are precision made on CNC equipment, balanced perfectly and all weigh exactly the same. That's very important.

9. Can I install the tuner or must it be installed by a gunsmith? Unless you are familiar with precision threading on a manual lathe, it would be best to have your gunsmith do the installation.

10. So, if I want one of these things, when and where will they be available? Stay tuned to BR Central, I'll advise you when the first batch is finished.


Guys, 2008 is going to be an exciting year! Best of luck to you.

Later,,

Gene Beggs



One advantage with this ring setup behind the muzzle crown is not having to worry about the possible and yet unproven small effects that gas venting may have on bullet precession, in competition guns, trying to maintain competitive edges that measure in the .010 ranges.

The downside to a light weight ring setup behind the muzzle crown is that is probably only good for fine tuning muzzle oscillations. This setup will most likely not have the weight range and fulcrum capability to find the largest and most optimal sweet spot for a given barrel.

The real payoff will be to see if the this "tuner-density altitude formula package" is able to lower competition aggregates on a consistent basis enough to become obvious to the top competitors, that they will in turn adopt the setup and start producing "hall of fame" points with it. Up until now, nobody has cracked the "tuner-d.a." formula with enough stellar competition results to make this a clear and proven advantage.

Good luck with it Gene............Don

Pete Wass
01-13-2008, 05:58 PM
When EVERYONE has a competatively tuned rifle,( Jackie has stated a few times that 75% of all the rifles on the line are out of tune at any given time), the HOF points then become available to 100% of those who are able to keep their rifle in tune, which should be at least 95%. Then Conditions, gun handeling and not commiting stupid mistakes become the only limiting factors.

I agree with Gene, 2008 will be an interesting year or has the potential to be one. Of course the naysayers will need to get on the band wagon . Will there be enough room? :D

BJS6
01-13-2008, 06:52 PM
Gene,

How does this set up work in terms of the load and barrel that is used with the tuner, I mean, how does the formula work with different barrels, bullets and powder weights ???

The reason I ask is that in previous posts here I have agreed 100% with your logic in respect to tuning a LV 6PPC with around 28.8 to 29.0 grains of N133 with a 68 grain bullet. My rifle shoots well at around 28.8 grains and I found that a change in powder weight was needed to keep the rifle in tune as DA changed, or was it just the temperature ?? Whatever cause it the load at that level certainly wasn't a constant in any given conditions.

My rifle also shoots well at 29.8 - 30.0 grains and in fact may shoot a bit better up there. The interesting thing with this load is that so far it seems to shoot just as well regardless of what the DA or temperature is. I have tested the load on the same day as the DA changed from -250 to +1500 and the load still seemed to shoot at any DA or temperature. I tested accuracy as the DA rose and at any DA I tested the rifle kept shooting. I didn't need to make any changes to the load.

What is your take on the load sensitivity vs the load level and the effect of the DA on the loads accuracy. Based on loading at two different load levels in my BR rifle and a lower "node" on a factory Cooper in 6PPC I reckon that the milder the load the more it is effected by changes in temperature and/or DA. That is to say that the hotter the load is that still shoots well the less effect the changes in DA will have, conversely the milder the load the more the accuracy seems to suffer with changes in DA and the more the load will need to be altered to get the tune back.

While the whole barrel vibration thing makes perfect sense to me the thing that is now puzzling me is this. If the DA reflects the effective density of the air and the changes in density alter the exit timing of the bullet, why do the hotter loads no get effected the same as the lower loads ????

Chisolm
01-13-2008, 06:53 PM
Gene
Any chance of some pictures?
James

Donald
01-13-2008, 08:46 PM
I have threaded the muzzel of one of my Bartlein barrels 36/inch and had my smith make me a bronze round weight that weighs about 5.5 oz. I lock it to the barrel with the time proven set screw with lead pellets under the set screw. I will admit that I don't have it figured out yet but I can tell you this that I can take a load that shoots in the fives and make it shoot in the 2's. just by adjusting the position of the tuner. I do also think that 36 threads /inch is a bit course. I only had to move the tuner 1/4 turn to have this effect. But then maybe it is the weight of my tuner. Who knows? Now if I can just figure out what direction and how much and what particular load to work with? These things do work, there is no doubt in my mind about this............Don

Donald
01-13-2008, 08:53 PM
BJ6S,
As to the high pressue loads......Jackie has stated that he always shoots in the "UPPER" load window. Personally I can't seem to get more that about 29.5 of 133 in a PPC case. Not unless I fill it to the brim. Maybe those that shoot these 30+ loads do load to the top of the neck and seat the bullet in a compressed load. I just don't know.........Don

Mike Marcelli
01-13-2008, 09:34 PM
One advantage with this ring setup behind the muzzle crown is not having to worry about the possible and yet unproven small effects that gas venting may have on bullet precession, in competition guns, trying to maintain competitive edges that measure in the .010 ranges.


............Don

Don:
While the effect that gas has on the base of the bullet of a centerfire rifle is not well documented, the effect of excess gas on the skirt of a lead pellet is well recognized. You can dramatically improve the accuracy of an air rifle by fitting it with a brake. From the Daystate website, respecting a review of their latest Field Target (FT) rifle:

"One of the other fine features of the FT-R is a muzzle flip compensator that ventilates the muzzle blast away from the pellet’s flight path."

The top drawer FT rifles all have this feature and I can assure you its not because of their tremendous recoil. This particular rifle also as a solenoid actuated firing pin -- so of course there is no need to relax the bolt. We could probably learn some things from these folks.

It might be interesting to combine a muzzle brake with a variable tuner to see what amount of accuracy enhancement is possible. Oh wait, Browning as already done that. ;)

Gene Beggs
01-13-2008, 09:52 PM
Gene,

Pertaining to FAQ #4, Here is question #11: Are you saying that you move the rings a predetermined amount in a given direction for incermental changes in density altitude? Or is each combination different because of the type and charge of powder being used, primer, bullet, barrel length, contour, and "personality"......or, in short, the factors that can and do effect the tune and accuracy of any given combination?

Interesting stuff...............
-Dave-:)

Dave, I'm sure there will be exceptions, but with all the varmint and sporter rifles I have worked with so far, once a baseline was established for that particular rifle, incremental adjustments to compensate for changes in density altitude were predictable and reliable. Of course, this assumes you don't change anything else such as primer, powder, bullets etc. A set of instructions will accompany each tuner and I will also offer one on one instruction here in Odessa at the tunnel facility.

Gene Beggs

Don
01-13-2008, 09:53 PM
Don:
While the effect that gas has on the base of the bullet of a centerfire rifle is not well documented, the effect of excess gas on the skirt of a lead pellet is well recognized. You can dramatically improve the accuracy of an air rifle by fitting it with a brake. From the Daystate website, respecting a review of their latest Field Target (FT) rifle:

"One of the other fine features of the FT-R is a muzzle flip compensator that ventilates the muzzle blast away from the pellet’s flight path."

The top drawer FT rifles all have this feature and I can assure you its not because of their tremendous recoil. This particular rifle also as a solenoid actuated firing pin -- so of course there is no need to relax the bolt. We could probably learn some things from these folks.

It might be interesting to combine a muzzle brake with a variable tuner to see what amount of accuracy enhancement is possible. Oh wait, Browning as already done that. ;)

Interesting Mike. I wonder if the effect on a subsonic air pellet that weighs much less, less mass, and momentum, than a centerfire bullet would see greater benefits from gas control?...............Don

Gene Beggs
01-13-2008, 10:20 PM
I have a 6.5 WSSM 1K BR rifle and a load that gives me unbelievable velocity spreads for long range (< 5 fps) but the groups are big, say .75" @ 100 yards. Other loads with a different powder give me small groups .25" @ 100 yards in good conditions but the velocity spreads are too large (25 fps). At 1000 yards, both give similar results. If I could tune the rifle to the low velocity spread load, I could substantially reduce my groups at long range.

Would this device be applicable in this case?

Doug, I could not possibly address all the questions this thread has generated, but yours is so important, I could not pass it up. Your situation is a classic example of how a tuner can be used to good advantage.

One thing I have discovered in recent times by chronographing every shot that goes down the tunnel is that there are some sweet spots in the powder charge that result in extremely low velocity spreads; this being completely unrelated to the sweet spots we refer to in regards to barrel vibration and bullet exit timing. It just so happens that in your case the two are diametrically opposed.

Yes indeed, a tuner can easily be adjusted to shoot your pet load. I have not worked with any of the thousand yard rifles with extremely long barrels; it may very well be that more weight will be needed to tune those rifles. We will just have to try it and see.

Gene Beggs

rstreich
01-13-2008, 10:35 PM
7. Are you concerned that someone else will try to patent your idea? No,,, I have already told you about it and it's been seen in public many times. No one can patent it.

Gene,

I'm afraid that last sentence isn't really true. I've seen dozens of patents issued for which there was gobs of prior art, even things that had become fairly common practice. My experience with this has been limited to software, but I'm sure it exists in other domains. It's just a question of what is disclosed and what is discovered.

As an example, don't forget the WSM.

robert

John Kielly
01-13-2008, 10:55 PM
We've been using a tuner consisting of two circular jamming nuts on a fine thread here in Australia for maybe 10 years now on target(Palma) & Match (1000-1200 yard) rifles. The only difference is these are machined with a couple of small flats, if you want to use spanners, rather than the capstan holes.

Rather than threading the barrel, these are attached using a prethreaded section thats loctited onto a .8" diameter machined section of barrel 1½" long.

Its proved to be quite useful with our match rifle barrels which are 32-34" long & limited by the rules to 2½ kg weight, equal to a Kreiger light Palma profile at 32". Most of us load for maximum velocity & minimum spread firs, then tune the barrel to optimise accuracy.

Gene Beggs
01-13-2008, 11:29 PM
One advantage with this ring setup behind the muzzle crown is not having to worry about the possible and yet unproven small effects that gas venting may have on bullet precession, in competition guns, trying to maintain competitive edges that measure in the .010 ranges.

The downside to a light weight ring setup behind the muzzle crown is that is probably only good for fine tuning muzzle oscillations. This setup will most likely not have the weight range and fulcrum capability to find the largest and most optimal sweet spot for a given barrel.

The real payoff will be to see if the this "tuner-density altitude formula package" is able to lower competition aggregates on a consistent basis enough to become obvious to the top competitors, that they will in turn adopt the setup and start producing "hall of fame" points with it. Up until now, nobody has cracked the "tuner-d.a." formula with enough stellar competition results to make this a clear and proven advantage.

Good luck with it Gene............Don


Don, it's getting late and I must call it a night soon, but I just had to address a couple of your comments. First of all, thanks for your feedback, you obviously understand this stuff very well.

You said, "One advantage with this ring setup behind the muzzle crown is not having to worry about the possible and yet unproven small effects that gas venting may have on bullet precession."

You are absolutely right and there is another pesky problem this design alleviates when using a chronograph. During early experiments with tuners, Charles Huckeba and I discovered that the muzzle blast from our cylindrical tuners, which extended one to two inches beyond the muzzle, rendered the Oehler 35 chronograph completely inoperative.

Earlier that day, the chrono had been working perfectly with my rifle, which did not have a tuner installed. I was about ready to trash the chrono when I remembered this. We screwed the tuner off Charles' rifle and 'Voila!' The chrono began working perfectly. This is how we discovered just how much gas was being directed forward along the bullet's flight path by cylindrical tuners.

Another thing that bugged me about large, cylindrical tuners was the fact that with them installed, I could no longer use my favorite, 2 liter soft drink bottle to catch the spray and patches while cleaning. :mad: With my new tuner, this not a problem and that's the reason I turn the last inch of the barrel in front of the tuner to .849, it perfectly fits the two liter plastic bottles. :D :D

At my age, it's the little things in life that really count. :p :p

Oh yes,,, one more thing. You said "The downside to a light weight ring setup behind the muzzle crown is that it is probably only good for fine tuning muzzle oscillations. This setup will most likely not have the weight range and fulcrum capability to find the largest and most optimal sweet spot for a given barrel."

This is a common misconception and myth that has resulted from written articles and discussions on this forum that mistakenly said, "There is only ONE, big, barrel-stoppin' node and the only way you can find it is by placing large amounts of weight BEYOND the muzzle." This is simply not true.

The muzzle goes through several complete cycles of vibration as the bullet travels down the bore; all of which are exactly the same frequency and amplitude. The only one that counts is the positive peak occurring at bullet exit. It is surprising how little weight it takes to tune the barrel.

Later,

Gene Beggs

Don
01-14-2008, 02:33 AM
This is a common misconception and myth that has resulted from written articles and discussions on this forum that mistakenly said, "There is only ONE, big, barrel-stoppin' node and the only way you can find it is by placing large amounts of weight BEYOND the muzzle." This is simply not true.

The muzzle goes through several complete cycles of vibration as the bullet travels down the bore; all of which are exactly the same frequency and amplitude. The only one that counts is the positive peak occurring at bullet exit. It is surprising how little weight it takes to tune the barrel.

Later,

Gene Beggs

Hi Gene,

Actually, there are several different frequencies and amplitude oscillations that are propagating the barrel during the firing sequence, and what I was describing was the most likely occurance of a light weight pre-muzzle weight system only having the capability of tuning the vary highest frequency motions, 6-9 khz range, which are very consistent but small in their barrel motion effect, compared to some of the lower frequency motions that would require greater weight and leverage effect in order to change their tune.

I am definitely not suggesting the Calfee thin-barrel-heavy-tuner-weight protocol that theoretically stops barrel motion at bullet/muzzle exit.

Maybe only high frequency fine tuning with density altitude variations will prove to be noticable enough to affect competitive aggregates. Lets hope so............Don

Doug Rumbaugh
01-14-2008, 12:39 PM
Doug, I could not possibly address all the questions this thread has generated, but yours is so important, I could not pass it up. Your situation is a classic example of how a tuner can be used to good advantage.

One thing I have discovered in recent times by chronographing every shot that goes down the tunnel is that there are some sweet spots in the powder charge that result in extremely low velocity spreads; this being completely unrelated to the sweet spots we refer to in regards to barrel vibration and bullet exit timing. It just so happens that in your case the two are diametrically opposed.

Yes indeed, a tuner can easily be adjusted to shoot your pet load. I have not worked with any of the thousand yard rifles with extremely long barrels; it may very well be that more weight will be needed to tune those rifles. We will just have to try it and see.

Gene Beggs

Thanks for the reply, I have the barrel in the closet waiting to try the tuner on it. I have several barrels for the rifle so I can save this one for tuner testing when the oportunity comes around.

Doug

BJS6
01-14-2008, 02:06 PM
Just in case you missed it before Gene, a slightly altered copy/paste of my previous post:


Gene,

How does this set up work in terms of the load and barrel that is used with the tuner, I mean, how does the formula work with different barrels, bullets and powder weights ?? Surely the adjustment needed relative to DA changes would depend on the load used.

The reason I ask is that in previous posts here I have followed 100% your logic in respect to tuning a LV 6PPC with around 28.8 to 29.0 grains of N133 with a 68 grain bullet. My rifle shoots well at around 28.8 grains and I did find a tie up between DA and the load change needed to keep in tune.

However, my rifle also shoots well at 29.8 - 30.0 grains. The interesting thing with this load is that so far it seems to shoot well regardless of what the DA. I have tested the load on the same day as the DA changed from -250 to +1500 and the load still seemed to shoot at any DA or temperature. I tested accuracy as the DA rose throughout the day and at any DA I tested the rifle kept shooting. I didn't need to make any changes to the load to keep the tune, there was no sign of vertical creeping in at all.

What is your take on the load sensitivity vs the pressure level and the effect of the DA on tune. Based on loading at two different load levels in my BR rifle and at another lower "node" on a factory Cooper in 6PPC it seems to me that the milder the load the more it is effected by changes in temperature and/or DA. That is to say that the hotter the load is that still shoots well the less effect the changes in DA will have, conversely the milder the load the more the accuracy seems to suffer with changes in DA and the more the load will need to be altered to get the tune back.

While the whole barrel vibration thing makes perfect sense to me the thing that is now puzzling me is this. If the DA reflects the effective density of the air and the changes in DA alter the exit timing of the bullet, why do the hotter loads no get effected the same as the lower loads ? The bullet is still travelling through air at a different density to what it was previously tuned in, why is the hotter load not effected just the same ?

I figure the change in tune is not just an air density thing but a combination of the burning characteristics of the powder at different pressure levels and the effect the air density has on the bullet timing and how that relates to the barrel vibration cycle. It seems to me that the powder burn thing is a very big part of the tune and a tuner doesn't have any effect on that. Is it maybe a case of a tuner masking the "problem" rather than fixing the problem which is in fact the effect that the ambient conditions have had on the powder burn ??

Just throwing some thoughts out there as I try and get my head around how this stuff works.

Bryce

Gene Beggs
01-14-2008, 08:23 PM
Bryce, your posts are well written and suggest that you have a good understanding of the various aspects of tuning.

In your posts above, the main question I am hearing is, "Why do some loads, usually in the upper window, seem to shoot well regardless of density altitude?"

The only explanation I can offer relates to something I have learned only in the past year and that is; there are some loads that exhibit unusually small spreads in muzzle velocity. I don't know why, but when you get the load just right, something happens that often results in single digit extreme spreads with the same powder and components that just a few moments ago, were giving as much as 45 to 50 fps spreads. And this with carefully weighed charges!

There's something going on that I do not understand. If the powder relied on ambient air for its source of oxygen, as does an internal combustion engine I could see how it would be necessary to achieve the optimum mixture setting, but gunpowder does not need a source of oxygen; it generates its own, if I understand correct. It must have something to do with achieving an optimum pressure. There are some cartridges that, with normal loads, naturally exihibit extremely low velocity spreads. I'm thinking of the 30 BR's, Jackie's 30 PPC and many of the thousand yard cartridges. For example, most of the shooters that do well with the 30BR tune it to about 2985 fps and in this range, it typically shows single digit velocity spreads. They shoot the same load day in and day out everywhere they go.

On the other hand, for years, with the 6PPC I rarely saw extreme spreads less than 25 fps and it was not unusual to see 47, or 53 fps! And this with carefully weighed charges. I will never forget one occasion where I shot a tiny dot in the tunnel with a 6ppc. I had been dinking around with light loads and could not get anything together. I was just about ready to trash the barrel when Charles Huckeba called. I told him what was happening and he said, "Put 30.2 grains of 133 in it and see what happens." The rifle put the next five shots into about a .120 with an extreme spread of 6 !

As most of you know, if we could load ammunition that had NO variation in muzzle velocity, tuning as we know it, other than optimizing seating depth, would not be necessary. Tuning so as to time bullet exit to coincide with muzzle stop is our way of minimizing dispersion caused by variations in muzzle velocity. It may very well be that when you get the load just right, nothing else matters. :rolleyes:

When you figure it out, let me know. :D

Later,

Gene Beggs

BJS6
01-14-2008, 10:11 PM
Thanks for the feedback Gene,

What you are saying makes sense, like you said, if the velocity was always the same with any old load then presumably the rifle would shoot well with all loads and at all velocities. Unfortunately that isn't the case of course !

I haven't chronographed my loads to get velocity spread figures so I must do that and see what I see. Perhaps the hotter loads simply don't exhibit the same velocity spread as lower loads due to the pressures involved ? I know one 10 shot group I fired at 200 metres (around 220 yards) had 0.20 total vertical spread, that was 30.4 grains N133 with a 66 Ultra, the velocity spread would logically be pretty low to achieve that.

Many thanks, keep up the good work.

Bryce