barrel tuner experiences

[AusFclass]

im working with a new barrel and have found a load that really hammers. . . 1/2" @ 300 ;D

BUT. .

after 2 firings 1 in 5 cases are getting loose primers :-[ so i think ill have to drop the load by 1gr.

during development the lower load had virtually the same ES but the group was around 1 1/4" so i believe that the LOAD is tuned well enough to do the job.

i havnt had any experience with tuners before but would it be possible to tune the harmonics of the barrel to shoot as well as the hotter load?

one of the problems is that the barrel is 30in long HV profile and the rifle is very close to weight limit. so how much weight would i need to influence the harmonics of the barrel?

 

[TonyR]

Give Butch Lambert a call at Shade Tree Accuracy. He has been doing things with tuners and told me about some sort of sticky weight tape used to balance golf clubs that can be used to tune barrels.

 

[AusFclass]

anyone ??

 

[BoydAllen]

Barrels tend to vibrate based on their length and stiffness. Your good load is probably such that the bullets that are forming a group are exiting at an advantageous point in the barrel's swing, near the top, on the upswing (Read on this topic on Varmint Al's web site.) The reason that your slower load has problems is probably that the bullets are exiting later in the barrel's swing, possibly after it peaks. What you need to do is to slow the barrel's swing so that the slower load is exiting at the same point of the barrel's swing as the hotter load was. Adding weight to the muzzle will do this. You can add some weight and then retune your load. As long as it is secure, the method of attachment can be fairly crude. The reason that rimfire tuners have to be so finely adjustable is that the ammunition is what it is. With CF, you can get close and fine tune with the load. This will undoubtedly give the shiny machined and expensive crowd hives. So be it.

 

[AusFclass]

yeah i had a read of varmit al's the other night and this section below seems to be good in theory!

AVERAGE VELOCITY BULLET.... Possibly the sweet spot occurs when the bullet, with the average velocity, for a particular load, exits the barrel just before the peak of its upward swing.

FASTER BULLET.... A faster bullet will exit the barrel earlier and exit slightly before the average velocity bullet and the angle of the upward swing of the barrel will be slightly less. So the bullet's launch angle is slightly less, but the bullet is going faster and drops less.

SLOWER BULLET.... A slower bullet will exit later and the barrel's vertical swing will be higher and at a steeper angle when the slower bullet exits. The bullet is launched at a higher angle but is slower and will drop slightly more.

ill have to weigh my gun again with the new barrel and see how much weight i have to play with. i think a .22 style tuner will be out of the question but a smaller version might be a possibility.

how much weight that will be required and the distance that it needs to be mooved is the a bit unknown.

boyd i like your theory of adding weight then load tuneing again to the altered harmonics.

 

[BoydAllen]

Let us know what happens.

 

[Wild_Bill]

first sounds like you are runnig to fast a powder and to hot if you are killing the cases that fast. as for a tuner as heavy as you can is best we make them up to 300gr so 1/2 a pound for realy heavy barrels but lighter profile barrels like a light palma a smaller tuner works well. i would make it as heavy as you can to stay in weight then you will just have to move it further to get a different node over a heavier tuner any weight that is added or mover will influence the group so just work with the weight you have but i like them heavy on a thick barrel over 1" at the muzzle.

Cheers bill