Buy a tuner or not?

[KennyB]

The targets were shot from the shoulder with iron aperture sights.

Hi Bryan, as Kevin so rightly says (although I may slightly disagree with his percentages) the errors from hold, aim and conditions will make it very difficult to objectively rate the groups. The vertical might be down to you or might be down to the barrel/ammo.

What I have been doing this summer is ammunition testing using SCATT (either from the shoulder or firing from a bipod) to confirm Point of Aim and quality of Hold/Release.
I have had a few batches of selected ammo that tested well from a fixed rig but when it came to shooting from the shoulder (with SCATT indoors at 50m on electronics) it became apparent very quickly that one batch put the shots where I was aiming them whereas the other batches produced unexplained stray shots.
I've seen similar results with other shooters too - shots that SCATT would say are deep 10's but which print low with selected ammo...

That said, I use and believe in tuners - I have one for each of my barrels. They seem to be working for me this week...

Ken.

[Tim S]

To complicate things, I have found that testing a barreled action "naked" and then adding a tuner mass or extension (or both) is also unreliable. Adding that much mass or length seems to be to great a change, and in my testing and rifle development has never worked out well.

kev

Hi Kevin,

so if a barrel/action shoots well with a tube fitted, swapping to a tuner-tube of similar weight and length would give a fighting chance of seeing an improvement, allowing for operator incompetence, or at least upset things the least?

Tim

[Bryan996]

These are good targets IMHO.........I would take them most days in pretty good conditions!! I have found that I gain more reduction in group size just working on hold and aperture size...... I would take a 197 @ 100 yards on that target any day of the week

Thank you for those positive comments Kevin, I seem to do most of my training by myself these days so it means a lot to get good feedback, especailly from someone of your standing. One question for you though, how do you find aperature size effecting group size?

I have had a few batches of selected ammo that tested well from a fixed rig but when it came to shooting from the shoulder (with SCATT indoors at 50m on electronics) it became apparent very quickly that one batch put the shots where I was aiming them whereas the other batches produced unexplained stray shots.
I've seen similar results with other shooters too - shots that SCATT would say are deep 10's but which print low with selected ammo...

That said, I use and believe in tuners - I have one for each of my barrels. They seem to be working for me this week...

Ken, I have found similar results. At the batch testing a lot of centre X actually tested slightly better than the midas, however shooting them both from the shoulder the Midas was clearly better. Ive attached a photo of the centre X shot on the same day and although the group isnt centred it shows the larger group size. I am beginning to realise that I do need to invest in a scatt system, maybe its time to sell the spare 1913 in the cabinet? Where in the UK do you shoot 50m indoors in electric targets? I didn think we had such a facility.

It looks like I'm going need to buy a tuner (after I've experimented with tube torque settings) to see if I can gain any benefits, everyone who has contributed who shoots high scores all seem to be using one! Thanks for all the replies

[kevin nevius]

Hi Bryan, as Kevin so rightly says (although I may slightly disagree with his percentages) the errors from hold, aim and conditions will make it very difficult to objectively rate the groups. The vertical might be down to you or might be down to the barrel/ammo.

Good morning Ken!

It is great to hear from you, I very much appreciate your posts and insight!

In my case, the percentages are probably more like 95% / 5%!! This old age thing is not for the timid! LOL Every year I find it a little more difficult to shoot the scores I had been shooting just a few years earlier. I will be at Bisley next year, and I was really hoping to see you during the visit - I hope you are planning to be there!

And using a system like SCATT during live fire testing (I hope that's what you are suggesting) would be a huge advantage for sure. There are few indoor venues (out to 50 meters) here, so I am not sure how practical it would be for most, but so valuable if someone can do it.

I hope you and yours are well,

kev

[kevin nevius]

Thank you for those positive comments Kevin, I seem to do most of my training by myself these days so it means a lot to get good feedback, especailly from someone of your standing. One question for you though, how do you find aperature size effecting group size?

Bryan:

Aperture size is unfortunately highly subjective, in conversations with others it amazes me how different the sizes are (at common distances on common targets), and how different people's perceptions are about the "line of white" they are comfortable with.

Personally, I will spend a lot of training time (in varying light conditions) testing aperture sizes. I start with a large line of white, and group shoot as I close the aperture size. I find that as the aperture closes, there will be a point where the groups explode (and wild shots / vertical dispersion are common). The sight picture will still look awesome, but shot placement becomes unpredictable. For me, my ability to group well and consistently mandates a tin line of white - so knowing where this point is is very important. Sometimes I think the rifle / ammunition is the issue, when it is actually too small an aperture setting for those light conditions.

I don't know of another way to establish these limits without just going out and testing. I think what is happening, is that there is some degradation of the contrast between beige and black due to the distance. As we bracket smaller, we start to infringe on this "grey area" and although the sight picture still looks great, we lose our ability to see the true target black position.

Just a theory...........any thoughts?

kev

[Bryan996]

Kevin - That all makes pefect sense. To be honest I misunderstood and thought you were referring to rear aperature size rather than the foresight aperature size, hence the question. I have trained with differant foresight sizes but do probably need to do more, especailly when the light levels increase or decrease dramatically outside.

many thanks Bryan

[kevin nevius]

Hi Kevin,

so if a barrel/action shoots well with a tube fitted, swapping to a tuner-tube of similar weight and length would give a fighting chance of seeing an improvement, allowing for operator incompetence, or at least upset things the least?

Tim

Hi Tim:

Yes, In my experience, if the two are very similar in weight and length you have a fighting chance.

There are two schools of thought it seems regarding tuning - one is the manipulation of mass, and the other the change in overall length and harmonics. I have tried and used both individually, but my best results have come from the combination of the two. If you can incrementally move the entire extension (changing both length and mass position) that, for me, has provided the most concrete and more importantly repeatable results.

Great question, thanks for the reply!

Kev

[Tim S]

Thank you Kevin,

That's encouraging to hear. I agree totally about the effect of weight on the position; I had a machinist friend make a weight that slipped over the tube to approximate the weight of some alu tuner tubes (it's amazing what beer can buy). The result was a majorly muzzle-heavy rifle. I think accuracy was slightly improved, but the overall effect was not. So one of the lighter carbon fibre tubes would be workable I reckon.

[gstarik]

Kevin,
Regarding front aperture,
We have aperture size,and ring thickness,which i find,very important for sight picture.I'm traying to have the thickness of the front aperture,at the same width of the white ring. When the front aperture is bigger,I like to have the the ring thicker,so they will always be the same width.I think it's easier for the eye to see 2 rings with the same thickness. Personally,when it's windy,I prefer 0.1 bigger aperture than my normal,because its easier for me to shade.
Guy.

[mgdietrich]

Mark D and Kevin always have their equipment in top shape.

From the look of the groups, there is potential for gain. A tuner could help, but as this was shot with iron sights in a sling how much error came from that?

I would shoot some more, and as Kevin said focus on shot execution. If that is perfect in these groups my then a tuner could help.

As Kevin said, you have to be ready for the weight gain. I took almost a half pound out of my stock this summer to make up for the barrel/tuner weight addition. Breaking a clean shot and fatigue are not to be over looked.

Morgen

[patriot]

Is the PRX calculation attempting to locate the muzzle at a node or crest (minimal or maximum amplitude)?

Mark

[PRX2500]

Good Morning All

PRX is based on the harmonic waves formed in a tube that is closed on one end and open at the other. In this configuration, there will always be a node at the closed end and an anti-node at the open end. Trick is find a length of barrel and tuner that achieves a node at the muzzle, with an anti-node at the mouth of the tuner at an applicable harmonic.

I would be happy to answer any questions you may have.

Thanks

Tony Purdy
The Purdy Prescription (PRX)
Does your rifle shoot "Purdy Good?"

[patriot]

You are implying that the length of the tuner helps to locate the node at the muzzle and not that it is effecting the bullet's path after it leaves the muzzle; correct?

Mark

[Shifty]

apparently the length of the tuner does have an effect on harmonics which is why the Starik tuners are all subtly different lengths - because they're made to measure for the length of your barrel using the formula mentioned above.

As I understand it, the weight of the tuner is what has the biggest effect on the barrel's tune (which is why tuners have movable weights) so the question I'd like answered is, how much effect does adding a sight to your tuner make? Obviously if you're shooting aperture sights you need to put a foresight on the tuner, but how much of a de-tuning effect does the addition of a foresight make?

[kevin nevius]

You are implying that the length of the tuner helps to locate the node at the muzzle and not that it is effecting the bullet's path after it leaves the muzzle; correct?

Mark

Hi Mark:

How could any tube or mass tuning device effect the bullets path "after it leaves the muzzle"????

I know the question was directed to Tony (my apologies)...........just curious?

kev

[Shifty]

If you read it again, he's confirming that a tuning device is having no effect on the bullet path once it's left the muzzle!

[Bryan996]

In this configuration, there will always be a node at the closed end and an anti-node at the open end. Trick is find a length of barrel and tuner that achieves a node at the muzzle, with an anti-node at the mouth of the tuner at an applicable harmonic.

Tony, if you're creating a node at the muzzle how would that ensure a low speed round leaves at a differant point to a high speed round? Are you not instead trying to create a wave form at the muzzle that has a wavelength that fits in with varying ammo speeds? The best explaination I read was on Guy's website:

"In order to compensate for the variation in velocity, we need to verify that both slow and fast bullets will exit the barrel on the upper slope of the cycle, so that slower rounds, which stay longer in the barrel, will exit it on a higher angle than faster rounds, thus compensating for the difference in velocities, and avoiding vertical dispersion. This is called “positive compensation”."

I also don't understand the effect the tube length has, other than to contribute to the total weight of the tuner, as once the round has left the muzzle its in free air inside the tube? The tube could be oscillating around all over the place around the bullet however its path was defined the moment it left the barrel.

btw I love the direction this thread has taken! Thanks for everyone's inputs.

[Tim S]

I also don't understand the effect the tube length has, other than to contribute to the total weight of the tuner, as once the round has left the muzzle its in free air inside the tube? The tube could be oscillating around all over the place around the bullet however its path was defined the moment it left the barrel.

Bryan,

I'm far from an expert, but I think the idea with length is to alter the vibration pattern while the bullet is in the barrel, so time the bullet's arrival at the actual muzzle coincides with the optimum point in the vibration. Essentially the tube changes the vibration waves; how and why this happens is beyond my pay grade.

[patriot]

You are implying that the length of the tuner helps to locate the node at the muzzle and not that it is effecting the bullet's path after it leaves the muzzle; correct?

Mark

Hi Mark:

How could any tube or mass tuning device effect the bullets path "after it leaves the muzzle"????

I know the question was directed to Tony (my apologies)...........just curious?

kev

Just establishing the foundation for further discussion on the topic. I often use a Socratic approach at work when we are innovating; should have explained. I want to understand this; keep an open mind, listen, and learn rather than arguing my bias. The objective is to frame up several contradictions to see if we can improve the model of what the heck is happening and what variables matter; which are correlation and which are causation.

Mark

One example, how can changing the receiver bolt torque 1/2 NM change the tune but shooting with the barrelled action clamped in a rest not? I can think of one possible explanation, but let's see what the wave theory tells us.

[patriot]

I also don't understand the effect the tube length has, other than to contribute to the total weight of the tuner, as once the round has left the muzzle its in free air inside the tube? The tube could be oscillating around all over the place around the bullet however its path was defined the moment it left the barrel.

Bryan,

I'm far from an expert, but I think the idea with length is to alter the vibration pattern while the bullet is in the barrel, so time the bullet's arrival at the actual muzzle coincides with the optimum point in the vibration. Essentially the tube changes the vibration waves; how and why this happens is beyond my pay grade.

So if it is only the weight, why does the length of the tuner matter? ... or the barrel length independent of the profile? Why does the nearly 30 inch barrel on my mini-palma shoot so well?

Mark

Quote from Joe Dirt: How exactly is a rainbow made? How exactly does the sun set? How exactly does the posi-trac rear end on a Plymouth work? It just does.