Gene Beggs
Active member
With all the talk of barrel harmonics, stopped muzzles, density altitude, water in the bore, this, that and everything else, it's enough to drive you crazy; isn't it? When the subject of tuners comes up, many just say, "Oh, to heck with it; it's all too complicated." 
If that's what you have been thinking, don't despair; it's not that hard; listen up, please.
"BARREL HARMONICS." Sounds pretty impressive; doesn't it? But in my opinion the word harmonics does not accurately describe what happens to a rifle barrel when fired.
Webster defines the word harmonic as, "of or relating to musical harmony; pleasing to hear."
Rifle barrels are anything but pleasing to the ear, and they don't harmonize with anything. When fired, they whip up and down like an old cane fishing pole, mostly in the vertical plane and the muzzle comes to a complete stop at the top and bottom of the swing. It is at one or the other of these stops that our bullets should exit as small variations in muzzle velocity result in the least dispersion. That's it; that's all there is to "tuning." You can time the bullet's exit with the powder charge or you can vary the vibration frequency of the barrel by moving a weight fore and aft on the barrel, whichever you feel is most convenient. Me? I'll use a tuner. I have tried it both ways and with the tuners of today, adjustment is quick and easy. I never have to adjust the load, I can never be caught at the line with a dozen cartridges that are loaded too hot. It's as easy as focusing a scope.
DENSITY ALTITUDE
This has caused a lot of confusion. Yes, changes in air density is the culprit that causes our rifles to go out of tune if we do nothing to compensate. You can monitor barametric pressure, relative humidity, temperature, dew point, wet bulb temperature, compute density altitude, etc., etc.; but do you know what the single most important thing is? Temperature!! Yes, changes in temperature have more affect on atmospheric density than all others combined. You can keep your rifle perfectly in tune throughout the day with nothing but an accurate thermometer and the simple formula that follows. Please remember that we are talking about short range benchrest group shooting with the typical 22 and 6mm cartridges in use today.
If you tune with the powder charge, decrease velocity 30 fps for each five degree increase in temperature and vice versa. With most powders, N133 being the most common, three tenths grain equals 30 fps. With most Culver type measures, one full number equals .6 grains. For example, if your favorite load is 54 clicks, and your rifle is perfectly in tune for the first match of the day when temp is 60 degrees, you will decrease the load to 53.5 clicks when temp reaches 65 degrees, 53 clicks at 70 degrees and so on.
Me, I prefer to use a tuner. I never have to change the powder charge and I find it much easier to remove the bolt from my rifle, slide it back so I can reach the tuner easily and make a small adjustment with the two little three inch tommy bars I carry around. Takes about fifteen seconds and I'm ready to go. No hassle, no pulling bullets and redoing a dozen cartridges, no cussing and fussin'. "But how much do you move the tuner, and which way?" you ask. Simple,
If the rifle is perfectly in tune, make a note of the temperature. Turn the tuner "IN" an eighth of a turn for each five degree increase in temp and vice versa. The tuner is marked with a single reference line. This line is placed at 12, 1:30, 3:00 4:30 etc. If the rifle dialed in for the first match of the day at 6:00 o'clock and temp was 60 degrees, move the tuner to the 4:30 position when temp reaches 65, 3:00 o'clock at 70 and so on. Understand? It's the simplest thing in the world but some try to complicate it.
Hope this helps. See you in Phoenix.
Gene Beggs
If that's what you have been thinking, don't despair; it's not that hard; listen up, please.
"BARREL HARMONICS." Sounds pretty impressive; doesn't it? But in my opinion the word harmonics does not accurately describe what happens to a rifle barrel when fired.
Webster defines the word harmonic as, "of or relating to musical harmony; pleasing to hear."
Rifle barrels are anything but pleasing to the ear, and they don't harmonize with anything. When fired, they whip up and down like an old cane fishing pole, mostly in the vertical plane and the muzzle comes to a complete stop at the top and bottom of the swing. It is at one or the other of these stops that our bullets should exit as small variations in muzzle velocity result in the least dispersion. That's it; that's all there is to "tuning." You can time the bullet's exit with the powder charge or you can vary the vibration frequency of the barrel by moving a weight fore and aft on the barrel, whichever you feel is most convenient. Me? I'll use a tuner. I have tried it both ways and with the tuners of today, adjustment is quick and easy. I never have to adjust the load, I can never be caught at the line with a dozen cartridges that are loaded too hot. It's as easy as focusing a scope.
DENSITY ALTITUDE
This has caused a lot of confusion. Yes, changes in air density is the culprit that causes our rifles to go out of tune if we do nothing to compensate. You can monitor barametric pressure, relative humidity, temperature, dew point, wet bulb temperature, compute density altitude, etc., etc.; but do you know what the single most important thing is? Temperature!! Yes, changes in temperature have more affect on atmospheric density than all others combined. You can keep your rifle perfectly in tune throughout the day with nothing but an accurate thermometer and the simple formula that follows. Please remember that we are talking about short range benchrest group shooting with the typical 22 and 6mm cartridges in use today.
If you tune with the powder charge, decrease velocity 30 fps for each five degree increase in temperature and vice versa. With most powders, N133 being the most common, three tenths grain equals 30 fps. With most Culver type measures, one full number equals .6 grains. For example, if your favorite load is 54 clicks, and your rifle is perfectly in tune for the first match of the day when temp is 60 degrees, you will decrease the load to 53.5 clicks when temp reaches 65 degrees, 53 clicks at 70 degrees and so on.
Me, I prefer to use a tuner. I never have to change the powder charge and I find it much easier to remove the bolt from my rifle, slide it back so I can reach the tuner easily and make a small adjustment with the two little three inch tommy bars I carry around. Takes about fifteen seconds and I'm ready to go. No hassle, no pulling bullets and redoing a dozen cartridges, no cussing and fussin'.
"But how much do you move the tuner, and which way?" you ask. Simple,If the rifle is perfectly in tune, make a note of the temperature. Turn the tuner "IN" an eighth of a turn for each five degree increase in temp and vice versa. The tuner is marked with a single reference line. This line is placed at 12, 1:30, 3:00 4:30 etc. If the rifle dialed in for the first match of the day at 6:00 o'clock and temp was 60 degrees, move the tuner to the 4:30 position when temp reaches 65, 3:00 o'clock at 70 and so on. Understand? It's the simplest thing in the world but some try to complicate it.
Hope this helps. See you in Phoenix.
Gene Beggs
