How to keeep in tune without DA meter

R

russell m

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I am starting this thread before I go to work. I wandering how you use a tuner if you do not have a DA meter to keep track of the DA? I wont be able to respond untill I get home. Hope everyone has a great day
russell m
 
Russel, IMO the jury is still out as to what effect Density Altitude has on tune in centerfire. I've been using a Kestrel 4000 for 3 years recording every target. Still haven't found a direct relationship. There is a relationship but it may not be direct/linear/singular.

Jim Borden was recording DA about 2 years before we started using the Kestrel 4000. Jim used one of the gizzies that drag racers use. I don't think he ever found a significant relationship.

Rimfire shooters use DA to determine which lot/velocity of ammo to use. Their loads are fixed within each ammo lot. In centerfire we dickie with bullet seating, powder, powder weight, etc. so we may not have kept the variables constant to really find the direct relationship.

I think there is a relationship but it may be a combination of DA and something else like temperature for example. And that relationship may not be linear. It may, for example, it may be logarithmic.

Airplane pilots live and die by DA but we, centerfire shooters, are not there just yet. If you are a new shooter $300 spent on bullets and powder may be more beneficial to you now.
 
DA and Centerfire

Many are concerned about how to accurately and inexpensively determine density altitude. As I explained in a previous post, you can make perfect use of your tuner knowing little or nothing about DA if you are willing to sacrifice two or three more sighters each time you go to the line. I frequently make use of the old reliable technique known as the "TLAR" method. That's right,, TLAR is an acronymn that means, "That looks about right." :D :D
Works gooooooood! :cool:

As explained in part 2 of, "How to use a tuner" it is not necessary to know DA for the first match of the day. By using the simple procedure described there you can quickly get your rifle in tune, and if you wish to make use of a formula for future adjustments that day, make a note of the DA and tuner setting. Then you can accurately predict what the new setting will be when the DA goes up, 250', 500', and so on. But if you do not want to fool with DA, you can simply repeat the procedure described in part 2 each time you go to the line.

Normally, from the cool of the morning to the heat of the afternoon, temperature increases incrementaly by about 20 to 25 degrees, so you know that as the day progresses, you will have to turn the tuner IN about one eighth of a turn for each 5 degrees increase in temperature. It's really not that hard at all, let me ask you this.

Your scope has a focus ring/knob that must be adjusted to get the sharpest sight picture each day; does it not? And although it could probably be determined with a computer program what the actual number would be on the dial at certain temperatures, you don't worry about the numbers; do you? Of course not, and the same thing applies to a tuner. You simply adjust the tuner until you have the rifle "IN FOCUS." :) Sure,,, if it was in tune an hour ago when the temperature was 70 degrees and the temp is now 75, you know it can't be off very far; huh? Sure, you know the DA has gone up a little, but not much and you do not have to start all over again. Turn the tuner IN an eighth of a turn and fire a couple or three sighters.

Hope this helps simplify things. In previous posts, I explained how and why changes in DA affect tune, and went into such detail mainly to help you understand what was going on, but you can make good use of your tuner just by using common sense. It's not hard. :D

Later,,

Gene Beggs
 
DA chart

Hope this goes thru. The chart is fairly self explanatory.
Go right to the current temp then up to the actual altitude of your firing line (pressure altitude) and add or subtract using the compensation chart for Baro depending on the baro reading from a handheld weatherstation. A horizontal line from there to the left side indicates approx. DA
Gene is probably right in his method described in part 2, but I plan to track the results using this chart...just for giggles.
Bryan
 

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Forgot to add

Sorry, I forgot to mention the Baro here in Raton is presently 23.27 and that number is not on the chart. You can use the chart with a "corrected" Baro from the nearest airport or weather station, or shift the chart according to the ACTUAL Baro at any location.
 
Meters we don't need no stinking meters

Weigh your powder.
 
Mike

I do weigh my powder, but using DA is more accurate than "Hey Jim, their some clouds commin in from the south and it getting cooler."
Bryan
 
Well I am home from work. Thanks for the replies.
Gene I have read all 5 parts on the tuner & also printed it. I plane on re-reading it several times. The jury is still out on weather or not to put a tuner on my new barrel. I think I may wait untill I shoot at the Tomball match on the 3rd of Feb. I understand now how to use a tuner without keeping track of the DA.
russell m
 
Bryan

that chart looks a lot like the ones in my old B-52 performance manual. Need to dig out my old E6-B handheld navigation computer and see if it will give me DA as well. It's been more than thirty years since I spun the scales on the back of that thing. Could be fun once I find it. :D
 
I enjoy reading the discussions on these concepts... nevertheless, I'll consider using a barrel Tuner and/or the DA theories after someone gets into the Hall of Fame incorporating them. But until then, I will focus on reading the conditions to the best extent possible...

Just my opinion,
Lee :D
 
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