Let's revisit Tuners please

[3081FTR]

Bump

 

[gunsandgunsmithing]

Thought I would dig up this thread and post a question.

Can tuners mask a poor load selection? Or is everything a function of ES/SD, width of powder node and harmonics within those for group size/shape - thus if numbers are good, powder width is good, simply use the tuner to alter harmonics to alter group size and shape. Or have I missed something?

From what I can tell if you have a barrel tuner if you select a load that has good numbers and a relatively wide powder node - i.e. where POI is not materially affected by increasing or decreasing the powder charge then a barrel tuner can be used to bring the group size and shape into what is desired.

Pictures below - a seating depth test - where bullets are seated closer to the lands in increments of .003". Each loaded round was measured and each batch of 3 was held within tolerance of .0005 +-.

First picture is seating out of the case (gets closer to the lands) left to right top to bottom. Second picture is the two depths I selected left group is closest to the lands and right group is .003" further away. (I had some trouble getting the image to display positioned correctly so hopefully it presents correctly).

None of these groups are particularly good but they are as good as I can make the ammunition. I then rotated the tuner out two clicks and re-shot two seating depths (second picture). Those two were selected as they showed the least POI change in the original test even though the group size was about 1 moa.

The impact on group size was significant - will it shoot at distance (600 and 1000), be capable of holding .5 moa vertical all else being equal? or is the tuner simply masking a bum load?

IME, tuners will allow you to extract whatever potential a given load and gun have to offer, and to maintain that same level of performance over a wide range, if not any range of temps and conditions.

So, if you have a gun that is only a .3 gun with Varget and 105's(both given for example) without a tuner, it'll still be a .3 gun with one.
BUT..if you have a gun that is a tack driver with lets say 30.0 grains of varget, but it falls off at 30.5, or when temps change significantly, a tuner will allow you to keep that 30.0 grain charge in tune throughout whatever conditions you have to work with.

So, yes, a tuner can "mask" a bad load by tuning the gun to shoot that load, but only within a certain range. It will never make poor powder choices or poor quality bullets into premium performing loads, though.

The benefit of a properly weighted tuner is a wider tune window and the ability to adjust to maintain tune in different conditions. The method that I recommend for tuning a rifle with a tuner is simple..put the tuner on and work up your load as normal..and never touch the tuner until the load is settled upon. Moving the tuner while doing load workup is akin to changing the powder charge twice before shooting it.

That said..if you're dealing with a cartridge that has a known good load..ie. 29.5grins of 133 in a ppc...you can typically go with that known load and fine tune it in with the tuner.

There is nothing complicated about using a tuner. In fact, they can greatly simply tuning and make nodes easier to find. Just keep it simple! It's so very easy to do that I can show someone with a known good gun and load how to use their tuner in 15 minutes or less, in good wind. ---Mike Ezell

 

[3081FTR]

Thanks for the reply Mike.

 

[swd]

The benefit of a properly weighted tuner is a wider tune window and the ability to adjust to maintain tune in different conditions.

Mike how do you chose the proper tuner weight? How broad of a variety of barrels will the same tuner work well with?

 

[gunsandgunsmithing]

Mike how do you chose the proper tuner weight? How broad of a variety of barrels will the same tuner work well with?

Testing..Fortunately, the same tuner weight does work well on a large variety of barrel's relative stiffness. I've found that anywhere up to 10-12 ounces works fine on hv and lv contours of typical br lengths. If weight limitations are an issue, lighter tuners still work, they just don't give as wide a tune window as one of more weight. My cf tuners are 7 ounces as shipped and can be taken down to 4 ounces. A replacement cover/weight can be added to add weight if needed. IME, the 7 ounces works well on any br contour barrel, as long as weight limitations and gun handling allow.

 

[swd]

Thanks, that's good information to know and makes buying one easier knowing they will work on a variety of barrels.

 

[Kings X]

, or when temps change significantly, a tuner will allow you to keep that 30.0 grain charge in tune throughout whatever conditions you have to work with.

Mike,
A couple of questions ref this statement :
1. How does the temperature change effect the size of the group? Could it be velocity difference?
2. If you know the effect of the temperature change - can you adjust the tuner to bring the group size back?

 

[savagedasher]

A tuner lets you adjust the vertical and horizontal of bullet movement . When the conditions changes I can adjust my tune at the range. My self I feel it wind changes rather then temperature changes that I have to adjust to. Larry

 

[gilmillan1]

I am with King on this one. It seems people do share on how to use a tuner and never touch it again. It seems simple. Find the powder charge node. use the middle of the node. Adjust seating depth to shrink groups, and then play with tuner until you shrink that group even more. However, the real question is how do you use a tuner when temperatures change? My rifle was shooting great at 50 degrees the first day of the match, but the second day at 30 degrees, i starting having vertical issues. How do you adjust in this case?

 

[savagedasher]

I am with King on this one. It seems people do share on how to use a tuner and never touch it again. It seems simple. Find the powder charge node. use the middle of the node. Adjust seating depth to shrink groups, and then play with tuner until you shrink that group even more. However, the real question is how do you use a tuner when temperatures change? My rifle was shooting great at 50 degrees the first day of the match, but the second day at 30 degrees, i starting having vertical issues. How do you adjust in this case?

It would depend on what direction that the tuner need to be move to adjust horizon in the tune. That is determined the off the point of aim tune. With my head wind tune it would take a small movement to the left from the action Larry

 

[Twoboxer]

. . . However, the real question is how do you use a tuner when temperatures change? My rifle was shooting great at 50 degrees the first day of the match, but the second day at 30 degrees, i starting having vertical issues. How do you adjust in this case?

No experience here, just what I would try first:

Since the temperature dropped, MV may have dropped also. If MV dropped, Barrel Time (time for the bullet to exit the barrel) increased. The adjustment would be to decrease BT, so adjust the tuner to "shorten" the barrel.

I guess if that didn't help, I'd go the other way

 

[gunsandgunsmithing]

No experience here, just what I would try first:

Since the temperature dropped, MV may have dropped also. If MV dropped, Barrel Time (time for the bullet to exit the barrel) increased. The adjustment would be to decrease BT, so adjust the tuner to "shorten" the barrel.

I guess if that didn't help, I'd go the other way

Almost! Keep in mind that there are lots of things going on when the firing pin falls and to my knowledge, no one knows all of the answers. That said, I was reading along , your post thinking " he's got it"...and then I think it went sideways. Tuners don't shorten or lengthen the barrel, relative to in bore time. But..they can change the frequency that it vibrates at. So, if you have a "slow" round due to temps or whatever, I think you have to slow the barrel down. Moving the tuner outward will lower the frequency, hence slowing the barrel...in this context.

 

[johnmyers]

Almost! Keep in mind that there are lots of things going on when the firing pin falls and to my knowledge, no one knows all of the answers. That said, I was reading along , your post thinking " he's got it"...and then I think it went sideways. Tuners don't shorten or lengthen the barrel, relative to in bore time. But..they can change the frequency that it vibrates at. So, if you have a "slow" round due to temps or whatever, I think you have to slow the barrel down. Moving the tuner outward will lower the frequency, hence slowing the barrel...in this context.

I have two of Mike's tuners and on my 6ppc I can't believe how it works. It's very easy, tune your load with it set on 0 , document what the outside temp is and keep in ammo box if you can't remember it (sometimes a problem with me) and adjust in if warmer and out if cooler. Can't be much easier. Getting 3 more barrels threaded for the second one.

 

[Twoboxer]

Almost! . . . Tuners don't shorten or lengthen the barrel, relative to in bore time. But..they can change the frequency that it vibrates at. So, if you have a "slow" round due to temps or whatever, I think you have to slow the barrel down. Moving the tuner outward will lower the frequency, hence slowing the barrel...in this context.

While I would (pointlessly) disagree with you that tuners don't effectively lengthen the barrel, I understand now that I was only dealing with one of the effects of firing a round. And only one of the "vibrations". The one I have concentrated on lol.

If instead you are trying to get a node to move, and you make the assumption that lower velocity means slower vibration frequency, the move would be to slow the barrel (frequency) down . . . which appears to be done by moving the weight away from the muzzle.

Have I got it now?

 

[johnmyers]

No need to overanalyze just do what has proven to work shoot and have fun

 

[Greyfox]

No need to overanalyze just do what has proven to work shoot and have fun

John has it. You don't need to know "why" it works, just how.

Rick

 

[gunsandgunsmithing]

While I would (pointlessly) disagree with you that tuners don't effectively lengthen the barrel, I understand now that I was only dealing with one of the effects of firing a round. And only one of the "vibrations". The one I have concentrated on lol.

If instead you are trying to get a node to move, and you make the assumption that lower velocity means slower vibration frequency, the move would be to slow the barrel (frequency) down . . . which appears to be done by moving the weight away from the muzzle.

Have I got it now?

John and Rick both nailed it but I'll give this one try.
Moving the tuner out lowers the frequency of vibration. This also does lengthen the overall barrel...tuner and all....IF the tuner is like mine and extends beyond the muzzle. What it does not do is that it does nothing to affect in bore time. A tuner doesn't stretch or compress the barrel so that the in bore time changes.

What makes your previous post incorrect is that lengthening the barrel is what will lower the frequency. Shortening it..or anything that's done to give the effect of shortening the barrel, raises the frequency, speeding up node travel, for lack of a better term. Bottom line, if for whatever reason, the bullet is in the bore for a longer time, then you want to "effectively" lengthen it. This could be described as making the barrel "wait" on the bullet.

Another thing, a barrel has it's own natural frequency that it will vibrate at, at a given temperature, regardless of how hot the load is or how big a hammer you hit it with. Amplitude is what changes with the size of the hammer used.

 

[johnmyers]

John has it. You don't need to know "why" it works, just how.

Rick

Thanks Rick I need to get it to work so I can keep up with you and Mike when I come south!!

 

[Twoboxer]

Thankyou for taking the time G&Gsmithing, I think I understand it now.

 

[Kings X]

In F-Class we are not allowed brakes. Anything sticking out pass the crown "might" be considered a brake. (??).
So many tuners are sleeves that adjust up and down the barrel behind the crown.
So if I get this right - as the velocity slows down (due to colder temperatures) - I move the sleeve forward.
Higher temperatures increase speed - so move weight back towards action.
I would agree that each barrel is different. But once you find the formula for barrel shape and caliber - the adjustments would be very close to the same.
So I would need to test to find out how much temperature effects MY velocity. Then how much adjustment to get it back to shooting the "baseline" size group.
Have I missed something?????