The Truth About Barrel Tuners

G

Gene Beggs

Active member
Guys, it has been my experience that you can talk about something till the cows come home, but the written and spoken word will take you only so far. There comes a time in which you must EXPERIENCE something first hand, before it becomes a reality to you. Let me ask you a question.

Would you be interested in learning the truth about centerfire tuners? No nonsense, speculation, or unproven theories, just the facts. Would you be interested in learning how to keep your rifle in tune at all times, at any yardage, regardless of atmospheric conditions? No mystery, myth, or complicated formulas; the only action necessary on your part is placing a dial in one of four positions, 12, 3, 6 or 9 o'clock? This can all be accomplished with a tuner that weighs only three ounces, and does not interfere with muzzle blast.

We could go on talking about it forever, but perhaps the time has come for you to experience it for yourself. Don't you agree? I have a suggestion. Why not pack your overnight bag, that's all you will need, and fly out to the Midland International Airport, located half way between the cities of Midland and Odessa, Texas. I'll pick you up, and in twenty minutes we will be at the tunnel facility where you will learn the truth about tuners. You can use my equipment (no hassles with airport security) and be assured of perfect conditions regardless of weather. In the tunnel environment we can concentrate on the task at hand without distractions.

This adventure will be less expensive than going to a match and you will learn things you might never discover on your own. What do you say; couldn't you use a little change of scenery anyway? Would this not be better than continuing with endless discussion and trying to rediscover the wheel on your own, when I can teach you everything you need to know about tuners in one session? A roundtrip ticket on Southwest Airlines is less expensive than fuel for your vehicle and you won't spend four days on the road. Relax, enjoy a drink and before you know it, you will be landing in scenic West Texas! Well, I think it's scenic anyway.

If at the completion of your training, you do not feel that what you have learned has been worth the trip, you owe me nothing and I'll pick up the tab at the best restaurant in town.

Some may feel this is a bold faced advertisement but I assure you, I have the best interests of our sport in mind. This type of instruction is badly needed. Has anyone else made such an offer? Has anyone else offered to SHOW you exactly how to use a tuner? I rest my case.

Gene Beggs
 
Gene,that is stretching it.

Scenic West Texas?? Change of scenery???. Man, what ever the Chamber of Commerce is paying you, it ain't enough.
Seriously, though, I would love to come out to your tunnel, if for no other reason than to just put our heads together, drink a cup of coffee, and swap lies. I wouldlove to seewhat my Rail Gun could doin there.
We probably have a few different ideas about tuners, but I would amagine in the end, the concepts are the same. At least we are actually shooting Rifles, rather than theorizing about what might happen, or exercising in wishful thinking.
What I am working on now is the idea of setting the tuner to a specific altitude-density as you do. While I have enjoyed a certain amount of success in Competition with what I have been doing, the fact still remains that I am using trial and error, and just plain guessing.
Maybe in the future.........jackie
 
Hey Jackie,,

,,, come on out anytime. Just hop on Southwest for the day and get out of that Houston madhouse for a while. We will do some visiting, a little shooting, and enjoy some great Mexican food. Who knows, we just might learn something from each other. We will have fun anyway. Let me know when.

Gene Beggs
 
gene, to be practical, and after

travel expenses, how much?

for me (and i would hope many others in differant venues) should be informative at least.

regards, tbob
 
Gene:

Its too bad you could not make the Cactus. Gary summed it up pretty well in the match report though -- quite a number of people were having difficulty tuning their rifles to the Phoenix conditions. (Gary also suggested that the cure for most folks was to use less powder).

I usually do not have a tuning problem at Phoenix. I've shot there using the same load in a miriad of guns and conditions so it took me WAYYYY to long to realize what the gun had been trying to tell me for two days -- it plain wasn't happy with my tried and true load.

Now, there were a LOT of folks with tuners at that match with various configurations. I'm sure you know many of them, as they are Texas shooters and they were struggling like the rest of us. In other words, the use of a tuner was not necessarily a cure for a rifle's poor performance.

Gene, I finally got the gun shooting, way to late to do any good, by dropping the load .7 gn. Before that, the gun was jumping in the bags and barking unhappily and the groups reflected the rifle's poor manners.

My point is, I think you're going to find, at some point, that a tuner is not a cure all and, specifically, that it can't cure a chemical imbalance. That is, I think the atmospheric and environmental conditions at Phoenix somehow changed the way the powder's deterrents functioned.

I'm not an expert in explosives, but powders (and necessarily their deterrents) are designed to work within certain parameters (namely, certain temperatures and pressures) and when you exceed those parameters, you transition from a controlled burn to an outright explosion (An extreme example of this would be to fill a PPC case with Bullseye (Please don't try this anyone)). We, as Benchrest shooters, generally operate at pressures close to or exceeding those the manufacturer anticipated, and sometimes, we are not going to get away with it. The gun may not blow up, but the powder's deterrents will lose their ability to control the burn rate and the powder will stop acting like a propellant and begin acting like more or an explosive (as perhaps evidenced by the change in a rifle's report).

Can I prove that this is what was happening at Phoenix? No. But, I believe it is a viable hypothesis based upon my knowledge of how chemicals react and my anecedotal observations. It has also led me to question how a tuner MIGHT effect group size in ways other than by effecting vibrations. But, that testing is still some time away.

Small ones.
 
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Mike ...

Mike Marcelli said:
I think the atmospheric and environmental conditions at Phoenix somehow changed the way the powder's deterrents functioned. QUOTE]

Not to be flippant or smart. I ask these questions as a student. How does a powder, sealed up tightly in a case, know what the atmospheric conditions and the temperature are, at the moment of ignition ??? How about if I preload in a different state ??? Art
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Mike,

I don't know any more about powder than you, probably know less, but I tend to agree that there is more to it than matching load or tuner setting to the Density Altitude.

I have been monitoring the DA and altering the load to suit, or at least testing the altered load. There is some correlation but it does not seem to follow the 0.6 grains per 1000 feet that Gene has talked about, at least not in the 30 grains N133 load range.

When I first installed a new barrel I shot it on a cool still morning with a DA of zero or a little less. At that 30.4 grains shot a dot, literally.

At a shoot with DA around 1000 feet a load of 30.1 grains shot well.

Maybe at the hotter loads the formula for keeping tune is different, seems to me I needed a 0.3 grain change to accomodate 1000 feet difference in DA.

Gene, have you messed with the tuner and how it alters tune with hotter loads, I understand you basically stick with 29.0 grains. Sounds like a lot of guys find the hotter loads hold tune better, presumably the better they hold tune the better off one will be even if they have a tuner to fiddle with to try and keep in tune.

Abintx - the theory seems to be that it is the density of the column of air in the barrel that effects the tune, that effects the resistance the bullet encounters when accelerating up the barrel. Sounds a bit of a stretch but think of the rate of acceleration and the fact that the air can only go one way, up that little 6mm hole !!

Bryce
 
abintx said:
Mike Marcelli said:
I think the atmospheric and environmental conditions at Phoenix somehow changed the way the powder's deterrents functioned. QUOTE]

Not to be flippant or smart. I ask these questions as a student. How does a powder, sealed up tightly in a case, know what the atmospheric conditions and the temperature are, at the moment of ignition ??? How about if I preload in a different state ??? Art
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Art:

Nothing flippant about it. I don't know all the answers. I'm not sure anyone knows the answers, including the guys that make the stuff. (Now I'm not being flippant either.) The fact is, the powder manufacturer's don't always achieve their intended result. Here's a link to one of the articles discussing the problems the military was having feeding the M-16, including our now famous IMR 8208. http://www.thegunzone.com/556prop.html

However, I'm going to break your first question down into two parts. The first, being, "How does a powder, sealed up tightly in a case, know what the atmospheric conditions . . . are at the moment of ignition" and the second being "How does a powder, sealed up tightly in a case, know what the temperature [is] at the moment of ignition ???"

I'll tackle the second one first: The temp of the case, unless its kept in some type of environmental chamber (i.e., a cooler) will equilibrate to the temperature of its surroundings. So, if it sits in a hot chamber for a while, its going to get hotter. If it sits in the sun, ditto. I was speaking to another shooter today and he made the unsolicited comment that he had a difficult time keeping his barrel cool at the Cactus and I had the same problem for a while -- until I started wrapping a wet paper towel around the barrel. I'm certainly not an expert on heat transfer, but the atmospheric conditions didn't seem to be condusive to keeping the barrels cool -- despite the fact that it was quite chilly on Sunday. So, temp COULD have been a factor, but I'm not certain that it was. In fact, I've shot the same load at 110 degrees in Visalia and it performed fine, so I'd speculate that temperature alone was not the factor (although perhaps heat transfer alone COULD be a/the factor?)

If poor heat transfer was a culprit, it could have caused higher than normal chamber temps and thus higher than normal pressures. (We wanted to set up a chrono on Friday, but were not permited to do so. A chrono might have shown higher than expected velocities, and thus higher than normal pressures could be inferred.)

I searched the internet for some written evidence that a deterrent's ability to control the chemical reaction could be influenced by internal pressure or temperature. Unfortunately, I couldn't fine anything, but my experience as a chemist tells me that at some point, a deterrent will stop acting like a deterrent (in essence, it will vaporize) and thereby allow the powder to burn more quickly than it would under optimum conditions. (Fire balls were shooting out of the muzzle of my rifle, that was unusual and indicative of an explosion versus a controlled burn). This phenomenon partially explains why some powders are more temperature sensitive than others.

Question No. 2 is tougher to address. In using the term "atmospheric" I wasn't trying to be specific. I'm not certain what atmospheric conditions played a part. Some folks tried to adjust loads using DA. That didn't work. As I said, the temp wasn't that high, so I don't know what factor temp played. Barrels were getting hot and staying hot, but I don't know what to attribute that too. If you re-read my post, I don't try to identify exactly what caused the load to "blow-up" I just wanted to point out that whatever was causing it was not going to be controlled by a tuner.

I generally do preload in another state. I didn't do that this time. But, I do load by weight and not by volume, and the same weight of powder I normally shoot would not shoot worth a darn, so I suspect that pre-loading would not have made a difference.

It would take someone with a LOT of money and time to figure out exactly why the "normal" loads weren't working in Phoenix. My post wasn't intended to offer any answers as to why, but to propose a hypothesis I believe is valid ((that a tuner is not going to correct a chemical problem) as well as to point out that the folks with tuners were having the same dilemma as us slubs without tuners.
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stiller said:
were you using at phoenix?
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The powder I always use. Tu3000 I shot the zact same load in my rail in Dec. 2007 and came in 8th in the 2 gun. Don't ask how I did at the Cactus -- it got real ugly after the LV 100. The gun wouldn't keep 2 bullets together until I dropped the load. Then I'd get two or three shots touching at 200 yds and have the rest go zinging out of the group when I got caught by wind changes or had to guesstimate and hold off because time was running out. Even with those wackey 3+" groups though, I had less than about a bullet hole of vertical, whereas my first group, with the hot load, had 1.2" of vertical.
 
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