Feedback From The Tunnel

[K Hope]

Ken, I can understand why you and so many others have a hard time visualizing what I have said for years about the rifle going out of tune because air thins out and weighs less as ambient temp increases. Your sentence above,

"Air in the barrel thinning throughout the day"

tells me that you are thinking only of that tiny bit of air 'in-the-barrel' and the insignificant weight it represents. Forget about that; if that's all there was to it the concern would indeed be negligible, but what you are overlooking is the fact that the air 'in-the-barrel' is confined in a long cylinder (the barrel) and the bullet (the piston) must push the contents out against the entire weight of the atmosphere and is travelling at around mach 2.7 by the time it exits the muzzle!

You can just imagine the backpressure this compressed air in the barrel exerts on the bullet as it accelerates down the bore toward the muzzle! The heavier the atmosphere, the more backpressure it exerts. If the atmosphere warms and air becomes less dense, backpressure on the bullet decreases, it accelerates quicker which reduces in-bore time and the bullets begin to exit early. That's why speeding the barrel up slightly (increasing vibration frequency) puts the rifle back in tune.

Hope this helps.

Gene Beggs

Not sure.

If I understand what you are saying is a less dense bore air increases muzzle velocity which to me seems contrary to the Pressure Exponent factor whereby a less dense air in front of the bullet (less confinement) would lower pressure and burn rate. - Negligible value.

As I see it, it is the higher operating temperatures ( lower bore gas densities) increasing energy produced. Pressure change per unit of time is directly proportional to Temperature. – High value.

All else being equal and not mentioning blow-by gases changing bore gas densities.

BR
Ken

 

[Richard]

Yes, probably so. I think the natural progression in regard to how inquisitive most people are about tuners goes something like....

1.)Sounds too good to be true. How does a tuner do THAT?

2.)Tries tuner, says...Huh! I'll be damn! It does do THAT!!

3.) Who gives a ? Send me another one.

Lol!

Or another common sight Here's draft one:

What do I do with a tunna?
posed to be more funna.
my groups ain't no smaller!
now who do I faller?
I done throwed it down in the holler!

 

[Jim Pag]

Yes, probably so. I think the natural progression in regard to how inquisitive most people are about tuners goes something like....

1.)Sounds too good to be true. How does a tuner do THAT?

2.)Tries tuner, says...Huh! I'll be damn! It does do THAT!!

3.) Who gives a ? Send me another one.

Lol!

Mike. It seem to me that a lot of people over complicate the use of a tuner. I've bought 5 of your tuners and I have 4 of Sid's, and one that Jackie Schmidt made me. I'm not the brightest bulb on the tree, but after 2 minutes worth of you explaining to me how to use a tuner, my game has improved 110 percent. I would not go to the line without one because they work that good. Sometimes just a 1/16th of an inch will bring it back in tune. I just can't understand why some people make a project out of using a tuner. If I can make it work, a blind monkey could make one work. Just my 2 cents worth.

 

[K Hope]

Mike. It seem to me that a lot of people over complicate the use of a tuner. I've bought 5 of your tuners and I have 4 of Sid's, and one that Jackie Schmidt made me. I'm not the brightest bulb on the tree, but after 2 minutes worth of you explaining to me how to use a tuner, my game has improved 110 percent. I would not go to the line without one because they work that good. Sometimes just a 1/16th of an inch will bring it back in tune. I just can't understand why some people make a project out of using a tuner. If I can make it work, a blind monkey could make one work. Just my 2 cents worth.

Hey Jim,

Not trying to diminish tuners or their ease of use but it is nice to at least see the big picture.

Take Care
Ken

 

[mwezell]

Mike. It seem to me that a lot of people over complicate the use of a tuner. I've bought 5 of your tuners and I have 4 of Sid's, and one that Jackie Schmidt made me. I'm not the brightest bulb on the tree, but after 2 minutes worth of you explaining to me how to use a tuner, my game has improved 110 percent. I would not go to the line without one because they work that good. Sometimes just a 1/16th of an inch will bring it back in tune. I just can't understand why some people make a project out of using a tuner. If I can make it work, a blind monkey could make one work. Just my 2 cents worth.

Thanks Jim!
Using them is super easy. I'm not sure why we can't have a new thread about the rest.

 

[mwezell]

Hey Jim,

Not trying to diminish tuners or their ease of use but it is nice to at least see the big picture.

Take Care
Ken

Ken, simply put, tuners let us time bullet exit with muzzle position. That's been covered in this thread. Nothing wrong with wanting to know more...I do too!

All I'm saying is that I wish you'd start a new thread for that discussion.

 

[Jim Pag]

Hey Jim,

Not trying to diminish tuners or their ease of use but it is nice to at least see the big picture.

Take Care
Ken

Don't make me come up and cross the border eh, and rap you over the head with one of Ezell's tuners and you'll see more than big pictures. Be careful what you say or I'll suggest to Trump that we build a wall up north to keep you Canucks out! Take care Kenny. Say hi to the Mrs. for me.

 

[jackie schmidt]

Last Sunday at the Crawfish, my Rifle started to loose it's tue at 200, so, before Mach 4 I gave it a 1/8 turn tweet. The fourth group was a .510, the last a .360.

That kept me in third place in the yardage, Grand Agg, and the Two Gun, the two shooters who beat me just beat me.

 

[Richard]

Jackie,

what thread pitch are you using? And what does your tuner weigh?

THX,,Richard

 

[Gene Beggs]

Okay Guys

I'm sorry! I got distracted and off course with this. But if you'll stay with me I think I can help you after I quit laughing!

Anyway,,,, back to the five match agg we were shooting. We got through the first three trips to the line in good shape and are now at the top of the leader board with a teen agg! The cases are loaded, we're just waiting for relay three to finish and for the range officer to say, "Relay one, shooters to the line!"

When we started match number one, temp was 60 degrees, tuner was set to 'zero.' After fouling shots and scope adjustment, our first three shot test group was not good, indicating the rifle was out of tune. Maybe not completely out but not what we wanted so the tuner was moved one mark in one direction or the other, I forget which way but that made it worse so we went back to zero and then moved the tuner one mark in the other direction. The next test group was smaller but still had a little vertical. One more mark in same direction and the rifle shot a dot!
So we were in tune with the tuner set to 2 marks 'in' from zero with a temp of 60 degrees. Match one went well.

Things were moving slow with the target crew and by the time the range officer called relay one back to the line for our second match, temp had increased to 70 degrees. My instincts were to bring the tuner 'in' one mark to compensate for the ten degree increase in temp but we decided to leave it where it was and accept maybe a little vertical as the wind had picked up and the group was likely to print more horizontal than vertical anyway. It was a good decision and although the group did indeed measure slightly vertical it was still a good group.

For match number 3, temp was up to 80 degrees so we definitely had to make a tuner adjustment. In match number two, it would have been better if we had turned the tuner 'in' one mark which would have removed the bit of vertical which was reflected on the target. Two marks 'in'' brought the rifle in tune and match 3 moved us into first place.


So here we are awaiting the range officer's call to the line for match number 4. Cases are loaded with exactly the same load used in match number one, tuner is set to four marks 'in' from zero.

Match 4 The range officer calls, "Relay 1 shooters to the line.

Winds have picked up some but temp remains 80 degrees. A two mark 'in' adjustment was made after match 3; one to correct for the ten degree increase from 60 to 70 degrees and another to compensate for the additional increase to 80 degrees. Tuner is now set to 4 marks 'in.' The test group on the sighter verifies that the rifle is in tune so we settle in to watch conditions and decide when to begin shooting. Six minutes remain in which to shoot our five record shots. Winds have been waltzing back and forth from one direction to the other with velocity slowing, becoming all but calm during the switch from one direction to the other. We know this pattern will repeat two or three times during the remaining six minutes so we will be ready when the next lull appears and machine gun our five record shots before wind picks up after the switch.

Sure enough, wind velocity is beginning to let up and comes almost to a standstill as the flag vanes meander about during the switch. This is what we've been waiting for; GO FOR IT! Shoot quickly but carefully, watching the flag tails for the pickup that is surely coming. Shots 1 through 4 go in a dot but as we are loading the fifth round the flag ribbons begin to rise as velocity increases. Do we stop shooting or continue, firing the last round by holding about a bullet hole of correction into the wind? If it was me, I know I would continue rather than stop and have to 'wait and pick' that last round.

And so, that's exactly what we did; fired the last round with a slight hold into the wind as the range officer calls, 'one minute, you have one minute to complete your firing.' And it's a good group! Good enough to hold on to the top of the leader board. One more decent group and we've got it won! 'Cease fire, cease fire, clear the benches, make the line safe.'

 

[jackie schmidt]

what thread pitch are you using? And what does your tuner weigh?

THX,,Richard

.900 36 tpi, weighs 4 ounces and has a snubber.

http://benchrest.com/attachment.php?attachmentid=20739&stc=1&d=1519872795

 

[JerrySharrett]

.900 36 tpi, weighs 4 ounces and has a snubber.

http://benchrest.com/attachment.php?attachmentid=20739&stc=1&d=1519872795

Jackies tuner brings up a couple of things. Is the tuner best ahead of the muzzle or behind it? Threading the barrel a long ways so the tuner can be moved ahead as well as behind might help answer that.

The other point, tuner clamped to the barrel or locked with jamming the weights together. I always slug new barrel to feel for irregularities in diameter. If I clamped a tuner over about 65 in/lb I could feel the clamped location.


.

 

[JerrySharrett]

On the Centerfire Forum in 2008 I started a thread “Tuners Phase II”. One of the responses from a well known BR experimenter follows. I’m copying this post because it adds some insite to the tuner discussion.

Thanks Jerry H...

“”Jackie,for short BR, I don't think stopping the muzzel will work as you think (always staying in tune). Here is why. When I was shooting the cerro safed unlimited barrels, there was never any verticle pattern. These would shoot big and round to tiny as the conventional tuning methods were used. Big was around .3 and small was around .1. These barrels were effectively equivilent to 3 and 4 inch crossectional diameter and therefore had very little vertical pattern in the off tune groups. I think that a LV rig has about .3 of verticle due to barrel/gun patterns caused by gravity and that is what is tuned by the various tuners designs. The other .3 of group dispersion is likely an internal ballistics issue. This internal problem is the one that I think drives everyone crazy. And it probably interacts with the gun/gravity induced verticle as well. I believe that tuners do indeed work, as I have tested them several times on BR rifles since the Boss came out. I wanted a wider, more stable tune which never panned out and I quit using them years ago. Using to tune mid match is certainly a good approach as you have proven many times but that was not what I as after. Personally, I want THE "lot" of powder that isn't finicky. And by the way, T wasn't it either. If you got T right, it would hold for an agg. Israelly 2015 in a 22 was as close as I have ever seen to tune in the spring and shoot all summer! Some of the other unobtanium powders were very easy to keep in tune as well. The key there, is to buy a bunch of powder you like and learn what takes to make it work. This probably relates to the internal group dispersion. As far as the beyond the muzzel thing, I believe the deep bored muzzel crowns that we tested years ago proved that you couldn't widen the tune window by keeping the crown parralell on axis either, which sorta fits the stopped muzzel concept that you are going to try. I look forward to hearing your results and regard your opinions with a good dose of credibility. There times that you just have to change the powder or load. I think it is generally agreed that 8208 series likes dry and V likes wet. Even though both can be made to work, it seems easier in their respective climates.””

.

 

[Richard]

Jerry, you bring up good ideas and

..

Jackies tuner brings up a couple of things. Is the tuner best ahead of the muzzle or behind it? Threading the barrel a long ways so the tuner can be moved ahead as well as behind might help answer that.

The other point, tuner clamped to the barrel or locked with jamming the weights together. I always slug new barrel to feel for irregularities in diameter. If I clamped a tuner over about 65 in/lb I could feel the clamped location.

a very good point. Testing with a long thread on the bbl sure does let you see what is going on.

Jackie, I'm sure you have tested your tuner from one end of the threads to the other. What did you see within that range? Have you ever tested with it behind the crown?
Also, you mentioned in a previous post a little about your snubber design. Would you mind telling us again what you did to come up with that?



.

 

[mks]

Here are two groups from a Shadetree tuner test on a 30BR. Which setting is best, and why? How would you interpret these groups?

http://benchrest.com/attachment.php?attachmentid=20741&stc=1&d=1519920969

 

[JerrySharrett]

Here are two groups from a Shadetree tuner test on a 30BR. Which setting is best, and why? How would you interpret these groups?

http://benchrest.com/attachment.php?attachmentid=20741&stc=1&d=1519920969

Measurement wise tuner 8. if tuner 6 the first two shots in a dot, the 3rd shot was out that shot could be caused by gun handling, wind, choke, anyrhing. If the first 4 go in a dot sometimes the shooter feels like that load will shoot through anything, 5th shot condition changes, bang, out!!

Judging groups, a lot is decided by watching the group form and watching the flags as each shot hits.


.

.

 

[mwezell]

Here are two groups from a Shadetree tuner test on a 30BR. Which setting is best, and why? How would you interpret these groups?

http://benchrest.com/attachment.php?attachmentid=20741&stc=1&d=1519920969

With my tuner, I'd move it to number 4 and try it there.

Setting 6 might be good if the shot that's out is condition related. Only the shooter knows and only most of the time.

Why is that, what I think? Both group size and shape tell me a lot about the state of tune that it's in. The two drawings appear to not be to scale, quite, so that makes group size a little bit more difficult to discern but...

I mentioned this early on in this thread, I think. With MY tuner, it's very common to see groups form when the gun is "completely" out of tune, that are big, round groups in the .3's. This is very typically about 3-4 marks from "in" tune. It should be noted that there's less moveable weight with your tuner, than mine.

Moving the tuner 1 mark yields groups like your #6, stairsteps, often with 2 in and one out...like yours. Group is likely to still be in the high .2's or .3's.

Moving the tuner a second time, by one mark, the groups are still stairstepping, but smaller. Maybe a mid .2

Move the tuner another mak, and it's most common that we now have a bullet hole or less of straight vertical. We're one mark out of tune at that point.

Move the tuner another mark and shoot a screamer, because you're now tuned pretty well to the hilt. In very good conditions, you may see 1/2 marks on the target but these small changes easily get lost in the noise.

As a rule, I seldom move the tuner if the conditions are worth more than the tune and my ability to read the flags. You quickly learn to correlate group size and shape to tuner settings. Working within a small needed range of tuner movement, sure makes it easy. Again, the above is relative to MY tuner. There are differences but they all work on the same principle and similarly.

As an aside, the above is a worst case scenario. You'll virtually never be more than a mark or two out unless you change loads are have the tuner off for some reason.

 

[mks]

Good eye, Mike. The holes are about 22 cal size so that it is easier to distinguish among the holes. The centers are right on. Here are the plots with closer to 0.308 size holes. Tuner 8 is a 0.146" group and tuner 6 is a 0.233".

Jerry, the sequence on tuner 8 was lower right, lower left, then upper. The sequence for tuner 6 was the middle one, then lower left, then upper right.

Conditions were early morning calm before any breezes kicked in. There were four wind flags out and none of them were moving. 100 yards.

Thanks for the responses so far.

http://benchrest.com/attachment.php?attachmentid=20742&stc=1&d=1519929057

 

[mwezell]

Good eye, Mike. The holes are about 22 cal size so that it is easier to distinguish among the holes. The centers are right on. Here are the plots with closer to 0.308 size holes. Tuner 8 is a 0.146" group and tuner 6 is a 0.233".

Jerry, the sequence on tuner 8 was lower right, lower left, then upper. The sequence for tuner 6 was the middle one, then lower left, then upper right.

Conditions were early morning calm before any breezes kicked in. There were four wind flags out and none of them were moving. 100 yards.

Thanks for the responses so far.

http://benchrest.com/attachment.php?attachmentid=20742&stc=1&d=1519929057

If I'm tuned to the mid teens, I'll likely leave it alone at a match. In great conditions, you might try 1/2-1 mark adjustment, toward 9. Did you shoot it at 4?

Something else of note...The tune repeats over and over, so going either way can make it better or worse. Two groups leaves out the important point of knowing what completely in and out of tune, with your barrel and tuner look like, in relation to tuner setting. I know what to look for with my tuner best. If I were a betting man, and I have been known to, I'd bet it shoots again, at 4.

 

[Boyd Allen]

Mike,With your tuner and rifle, what is the interval between settings that give perfect tune, and what does that represent in terms of movement along the barrel axis, in thousandths of an inch?