Tuners some info.

[Lynn]

mks
A couple years ago when Bill Calfee was telling everybody tuners were good and they ran him him off the website he was using two different loads to make sure his tuner was set properly.On my 300 Ackley heavygun I had one load with a heavy bullet and one load with as light bullet that I was testing with.I thought we were trying to make to widely spaced shots converge so I kept adding weight until they did.
After I posted my results Bill Calfee called me and told me how to set up my tuner.You want two very small groups not one.
Lynn aka Waterboy

 

[HuskerP7M8]

Landy,
That's it! Any results with different forend stiffness?

Cheers,
Keith

Keith,

I was out of town and my previous post was from a cell phone. Since it took about 30 minutes to compose it, I wasn’t gunna try it again!

I’ll keep this brief since I believe it’s slightly divergent to the intent of this thread. By that I mean Joe Friedrich’s Ultralight along with mine are rimfires and thus far, but I’m still trying, I’ve been unable to reproduce the sine wave pattern in POI that’s easily seen in ladder testing and/or tuner adjustment in centerfire rifle testing. I think it’s “probably” there, but it’s masked by the noise of rimfire’s inherent inaccuracy relative to the precision obtainable with centerfire.

Sometime during the next year I plan on testing the Ultralight in my tunnel but as of now....I have no data. Presently, Joe might be the best source to answer any questions about this but it could be an apples and oranges comparison since we’re talking rimfire.

Landy

 

[Gene Beggs]

Oops!

Gene:

I have a question about one of the things you wrote (I've read about half the thread) and I would be very grateful if you could tell me if I have it incorrectly.

In post #85 you wrote

Quote#1
"Expressed in terms of ambient temperature and again, assuming we do nothing to compensate, the rifle will go out of tune completely with an increase of 20 degrees F and come back into tune with another 20 degree increase."

That caught my eye, because I had been following a belief that TEN degrees put a rifle from full tune to out of tune, based on THIS quote from an article I got off a British shooting club's site, entitled "PPC Load Tuning Tips – by Gene Beggs" http://benchrest.netfirms.com/Standard Cartridges.htm

(GB) Gordon, I'm so sorry but the statement should read, "20 degrees puts the rifle completely out of tune."

"If the rifle is in tune and shooting dots at 27 grains, it will begin to show vertical at 27.3 grains and will be completely out of tune at 27.6 grains...... Since temperature is the main reason for changes in DA you can accomplish the same thing by using only a thermometer. The ratio is .3 grains per five degrees F" [implying that 10 degrees would put the rifle off by 0.6 grains -- or fully out of tune based on the first sentence I quoted....]

(GB) I'm so sorry but the sentence above should read, "The ratio is .3 grains per 10 degrees." A 20 degree increase in temp does indeed put the rifle completely out of tune if you do nothing to compensate. Sorry for the error."


Am I completely confused here? Is the difference between tune and out-of-tune 10 or is it 20 degrees?

(GB) It's 20 degrees. Sorry 'bout that.

The reason I ask is that the combination of (me and my rifle) are not yet accurate enough to be able to figure it out ourselves, but it would help me reduce ONE of my many errors if I knew roughly what to expect to change the load by for a 10 degree range. So I'm really asking a real question, not trying to give you a hard time or anything!

THANKS!
Gordon

Gordon you are SO right! And I am very sorry for the error!

In spite of my best efforts something like this falls thru the cracks from time to time. When it happens, I do my best to correct the mistake but what grieves me is that some have made copies of the posts that are in error. All I can do is make a sincere effort to get the word out and correct the error; I will do that immediately. Thank you for bringing this to my attention; you are very observant and are paying close attention to what is said. Good for you.

My corrections will appear in bold preceeded by (GB) in your post above.

I am reminded of a post by Boyd Allen in which he said,

"Only rocks are perfect; they just lie there and do nothing."

If we humans do and say things, we WILL make mistakes; huh?


PS (A few minutes later) Something else just came to mind and this is an appropriate time to say it.

My error above serves to remind us how difficult and in my opinion, futile it is to try to calculate exactly what the tune should be under a given set of atmospheric conditions. Why worry about it! You can forget all about numbers and let the rifle/barrel tell you when it is and is not in tune. FWIW

Gene Beggs

 

[Bob Kingsbury]

Gene

Have you ever used a powder in conjuntion with your tuner that
needed less adjustment than another powder. Example, powder A
will still shoot great, but the tuner must be closely monitored to temp,
while powder B is still ok across a wider span in temp and no adjustment.

 

[docsleepy]

Gene -- THANKS so much!

My rifle and I are so far only in the 0.375 area....so I cannot reliably distinguish one bullet hole (6mm) worth....but it DOES increase my inaccuracy when I'm out of tune (I just have to fire a lot more bullets to figure it out)

I *think* I found a node by laboriously firng a slew of bullets and graphing results....at one temperature. I was able to measure velocity also. To avoid burning out my barrel, it is very helpful to me to at least have a ballpark idea of where to work on subsequent days.

That's why it caught my eye. Helpful hints like what you wrote are extremely useful to people like me who are still learning this game, and not with a very fancy rifle.

Thanks for taking the time to let me know which is right.

Gordon

 

[Gene Beggs]

Have you ever used a powder in conjuntion with your tuner that
needed less adjustment than another powder. Example, powder A
will still shoot great, but the tuner must be closely monitored to temp,
while powder B is still ok across a wider span in temp and no adjustment.

Bob, I thought I responded to your post a moment ago but I must have absent mindedly deleted it instead of submitting.

No,, I can't say I have encountered a powder that seemed significantly easier to keep in tune but I believe there are cartridges that are. Jackie Schmidt's 30 PPC and the 30 BR's are known for being easy to keep in tune.

Gene Beggs

 

[Gene Beggs]

Gene, you stated that DA related tune repeats at 4000 ft cycles. In my test there was a 2.25 cycle change which surely would have shown some state of tune difference. I have seen small changes in DA which should not account for the state of tune going away that occurs when RH changes of 20% or more. At the last NBRSA nats ( think it was 98)at Fairchance there was a HOF shooter shooting big round .250+s in the LV 100. A 2 degree temp drop and a 30+% increase in RH occurred between match 2 and 3. A short rain shower occurred. He shot the next 3 groups in the zeros with temp coming back up 3 degrees but the RH stayed up. I asked him what he changed and he said absolutly nothing but had no idea why the gun suddenly went to shooting as it did the early morning SP matches 1 and 2. The normal daily progress is increasing temp, DA and dropping RH. There a clue there. I think RH affects the powder fouling. When it is high the brush goes through easier than when it drys out. I believe this surface change is affecting the rise time and thus the exit timing. The bullet spends over half of the barrel time moving the first two inches. When I used a Oehler 43, the consistancy of the rise time was critical to grouping size. A powder fouled out barrel shows erratic rise times and graphs. I do not doubt that tuners can be used to compensate for what is going on. But, what is really occurring?

Jerry, I'm sorry but I made a mistake in a couple of my responses to your post on density altitude. The in-tune condition repeats at 2000 ft intervals not 4000. Sorry. Instead of going back and trying to correct my mistake I thought it best to just delete them. Getting old and tired I guess.

Best regards

GeneBeggs

 

[Boyd Allen]

I may have posted this before, but a while back I was trying a new combination in my 6PPC and fired a two shot test group, under good conditions that was about as bad as they get, probably a bullet hole of paper between. I thought about it for a bit, decided that it had to be near to half way between nodes, changed the load .6gr, and the problem was solved, all because I had the good sense to remember Gene's post about their being about 1.2 gr. between nodes. BTW I followed that up with 5 shot groups that were just fine.

 

[Jerry H]

No problem Gene. I get things screwed up all the time. I think it is a requirement to stay in benchrest!

 

[Pete Wass]

"For All practical purposes",

Pete,
At the risk of adding to your torment, liquids CAN be compressed!

Cheers,
Keith

was the preamble to the liquids can not be compressed part, as I recall. I refused to believe it way back then. I guess the "for all practical purposes" part gives science a good bit of wiggle room, eh?

 

[jackie schmidt]

On Things Being Compressed

Anything can be compressed, if there is enough external force to accomplish the feat. The problem is applying the pressure.

If you don't believe this, think of the concept of a Neutron Star, or even a Black Hole. Those that know this sort of thing state that a piece of a Neutron Star the size of a basketball would weigh as much as the entire planet earth. Keep in mind, it started out as a gasous star, and by the force of tremendous gravitation forces, is compressed at the atomic level..

The catch is we on Earth do not poccess the means to apply the kind of force that it takes to compress materials at the atomic level, ie, where individule components of the atoms themselves are actually squished together.

Under normal circumstances, we say that liquids cannot be compressed. If they could, our entire concept of hydraulics would be thrown askew.........jackie

 

[mks]

was the preamble to the liquids can not be compressed part, as I recall. I refused to believe it way back then. I guess the "for all practical purposes" part gives science a good bit of wiggle room, eh?

Pete,
It does. Einstein said, "Models should be as simple as possible, but not simpler." Applied to liquids, this means that incompressible works most of the time. If you are talking about water at the bottom of the ocean, or black holes, incompressible is too simple a model. I had a professor once who said that an appropriate answer to most any technical question was, "It all depends."

Cheers,
Keith

 

[pacecil]

Not only can liquids be compressed but there are several different compressors built to compress them. The process used to manufacture some plastics (most common is polyethylene) uses high pressure in the manufacturing process. These can range up to 100,000 psi.
Silicone fluids are compressible which makes them a slight problem when used as brake or hydraulic fluids. The compressibility of a fluid has bearing on it's freezing properties, which means the point at which it turns into a solid.

The compressibility of all substances can be found in most physics handbooks. It has the units of square inches per in pound. For air it's .068, for water it's 33333, for steel it's 35714.

 

[Greg Walley]

I think RH affects the powder fouling. When it is high the brush goes through easier than when it drys out. I believe this surface change is affecting the rise time and thus the exit timing. The bullet spends over half of the barrel time moving the first two inches. When I used a Oehler 43, the consistancy of the rise time was critical to grouping size. A powder fouled out barrel shows erratic rise times and graphs. I do not doubt that tuners can be used to compensate for what is going on. But, what is really occurring?

Jerry,

This is an interesting tidbit of information that you’ve posted here. I remember we had discussions about ten years ago on how to get fouling under control with a “magic solvent”, which unfortunately I have yet to discover. If I remember correctly, we both agreed that mechanical abrasion is the best way. I've never found a better way.

After examining hundreds of used barrels across a broad continuum of initial bore condition and wear, I’ve never been able to reliably predict if a barrel is “shot-out”, or good or bad simply by evaluating the condition or finish of the bore. However, I suspect that when a barrel starts to foul uncontrollably is when it is past its prime. Likewise, it may be true that varying degrees of powder fouling due to load variations might be one of the most important variables.

I believe it’s almost impossible to prove at a reasonable confidence level what constitutes a significant change in “tune” by manipulating single variables during typical match conditions…the only exceptions in my experience are powder charge and seating depth. In fact, I can’t say with certainty that neck tension is always a significant variable.

George Ulrich’s post on expansion measurements is very interesting. It will be interesting for me to see what he discovers. I’ve always suspected that a great “hummer” barrel is simply a barrel that has its muzzle pointed in the same place from shot to shot after it goes through its vibration cycle and thermal changes - and also fouls in a consistent manner.

I have some ideas on a metrology experiment for seeing these changes during the course of fire. I hope that someday I can find the time and resources to get the project going.

Greg Walley
Kelbly's Inc.

 

[alinwa]

Jerry,

This is an interesting tidbit of information that you’ve posted here. I remember we had discussions about ten years ago on how to get fouling under control with a “magic solvent”, which unfortunately I have yet to discover. If I remember correctly, we both agreed that mechanical abrasion is the best way. I've never found a better way.

After examining hundreds of used barrels across a broad continuum of initial bore condition and wear, I’ve never been able to reliably predict if a barrel is “shot-out”, or good or bad simply by evaluating the condition or finish of the bore. However, I suspect that when a barrel starts to foul uncontrollably is when it is past its prime. Likewise, it may be true that varying degrees of powder fouling due to load variations might be one of the most important variables.

I believe it’s almost impossible to prove at a reasonable confidence level what constitutes a significant change in “tune” by manipulating single variables during typical match conditions…the only exceptions in my experience are powder charge and seating depth. In fact, I can’t say with certainty that neck tension is always a significant variable.

George Ulrich’s post on expansion measurements is very interesting. It will be interesting for me to see what he discovers. I’ve always suspected that a great “hummer” barrel is simply a barrel that has its muzzle pointed in the same place from shot to shot after it goes through its vibration cycle and thermal changes - and also fouls in a consistent manner.

I have some ideas on a metrology experiment for seeing these changes during the course of fire. I hope that someday I can find the time and resources to get the project going.

Greg Walley
Kelbly's Inc.

oooohhh good post, lotsa' heresy in here

gottaluvvit

al

 

[upandcoming]

Gene - can you explain?

First of all, this was one fantastic thread!

However, I have a slightly problem understanding the two quotes I have pasted below. Could you elaborate or perhaps show me in the direction so that I can get a deeper understanding of this? First of all weight is less important, but the HV barrel could be "too stiff"? Where do I go wrong?

I have found the tuners very interesting, I have one of yours however have not been able to test it properly yet. But I might be forced to postpone that now since I was thinking about testing this on my HV rifle ...

As far as barrel length and contours are concerned, I have worked mostly with LV and Sporter rifles with lengths from 21 to 24 inches. All seem to respond exactly the same, but my friend Bryn Borras says my four ounce tuners do not work on his heavy varmint barrels. I'll have to do some experimenting in the tunnel using three rings instead of two on the HV rifles.

No not exactly; I experimented with different threads until I found one that resulted in exactly one revolution between nodes. I was delighted when I found that the actual weight was not critical but the distance moved was.

Hope this helps.

Gene Beggs

 

[Lynn]

Upandcoming
I don't shoot point blank I shoot spray and prey but my take is Gene has found hat his 4 ounce weight works well behind the muzzle on a skinny barrel profile.He adjusted his threads until he found one that works with repeatability at 1/4 turn increments.
On his comment that the amount of weight doesn't matter I find that to be completely 180 degrees out of sink from what I am seeing so he can explain what he means by it.
If you go to the new forum I have PM'ed you about you will get alot better information there than you will here in my humble opinion.
Waterboy

 

[Boyd Allen]

Lynn,
No, that would be rimfire that use skinny barrels with their tuners I believe that he has been mainly using light varmint contour, which is actually pretty hefty. Personally, given the nature of trying to make weight with a tuner for LV/Sporter (10.5#) I think that going a little slimmer than LV might be a good thing for rifle balance. Of course his unique stock design frees up some weight that would otherwise have to come from the barrel. http://accurateshooter.net/Blog/beggs3x900.jpg,
but for most of us, that shoot more conventional stocks, keeping a rifle within weight and in balance, with a tuner on board is a situation where every added oz. of tuner weight requires a reduction somewhere else on the rifle. A different design problem than is posed by even the lightest class in long range BR. Wouldn't you agree?

 

[Lynn]

Boyd
If you look back onto the work of Varmint Al and his modeling of the Calfee Sporter contour I can't for the life of me understand why this barrel profile hasn't been put through the ringer or modeled to the limit.
I have a 50.4 ounce Scott "Fudd" Hamilton tuner on a 1.450 straight cylinder barrel I will be shooting next friday,saturday and sunday at the NBRSA 600 Yard Nationals.On my lightguns 11-13 ounces seems to be ideal with a 30 inch Max heavy varmint contour barrel.
To my way of thinking I would design the gun around the tuner and not try and adapt a tuner to a gun that already has weight problems or concerns.In other words if it takes 12 ounces to work right my gun would weigh 9.5 pounds without the tuner no matter what needed to be done.
Lynn aka Waterboy

 

[upandcoming]

Ok - I am not sure if you misunderstood me, but when stated "does not work on HV" I get puzzled. The weight and threads are calibrated such that normal LV/Sporter barrels are maximum and half turn out of tune I get - but shouldn't a HV barrel just be more out of tune with respect to turns i.e. needs more adjustment before the node is found? As an example - LV needs maximum one half of a turn, HV needs twice the amount?

As for total weight I have no problem what so ever to make room for a tuner on my HV with respect to the total weight.