Load dev-how many shots does it take to dial in a rifle?

[Jarhead]

Wooo Hooo!

The barrel angle sensor was a success at the range!!!!

Next steps-

1. make a bullet exit sensor.
2. determine how many milrads per volt.
3, setup an adjustable mount so you do not have to spend 20 minutes tweaking position with wooden wedges before firing one shot.....

[JimTom]

Next level mate. Nice one. Well beyond my comprehension.

[TassieTiger]

Watching with interest.
Will the investment pay off - will be the question - the theory is there...Please keep updating.

[Jarhead]

Tassie,

Paid off? LOL. It already has! I once paid thousands for a holiday that really sucked. I have spent exactly $83 on this so far ( I already had the oscope) and the pleasure of success has made it worth doing!

I have decided to do this to shoot better and enjoy the process. I have spent enough of my life making money that I can choose not to with my favourite hobby. If I wanted to make a buck I would be looking at how to integrate this with iphone /android instead of the Tekscope as that is the only way it would make a viable business case.


When I get some usable data on the 6.5 it will be fun- I can work towards that less than 0.2 MOA target I set for myself.

I started working on a barrel sensor design- but stopped when I realised it will be exposed to muzzle blast. I need to understand the blast forces first as I don't want to send sensor shrapnel flying.

I did measure the device scale.- 6 volts per miliradian

I also thought about a mount- I have one for a dial gauge that I think will be exactly what is needed- will play with it this afternoon.


So far the only real data I have gleaned with it is that my .22 whips through about .23MOA.

[TassieTiger]

Paid off - $$$ is not what I meant.
I Meant with improved accuracy over all...

Sometimes I’ve noticed with trying to gain accuracy, you try different this, different that, and at times get results that don’t meet expectations. That’s all.

[Bugman]

Two shots at 25m then adjust, then 2 more at a 100m. Zeroed in.

[Jarhead]

Hey Tassie,

I haven't forgotten about the heat theory.......

Theorising- There are two factors I can immediately think of that would affect POI accuracy. One is that the speed of sound (and the p waves travelling through the barrel) changes with temperature. So temperature will change your optimal barrel time (OBT). This will affect accuracy. Come to think of it- heat will make the barrel crown grow with expansion- resulting in a looser crown on the bullet which can also affect accuracy. You could bond a strain gauge or two to the barrel to measure this. Hmmmm- future project in the works.....

I said two factors but now it's three.......

As the barrel heats up it will expand (thinking about your rails again). The longer length will change the whip harmonics slightly. This will change the positive compensation from the barrel whip that offsets bullet velocity changes. I might be able to measure this with the barrel angle sensor.

LOL, my brain keeps going.....now its possibly four factors.....The whip harmonics are transverse waves, the speed of which are also a function of temperature in a gas. Need to check if that same rule also applies to solids.

Hmmm- wave propagation is affected by density- density changes with temperature.

I'll admit those brain cells have been soaked in all sorts of "substances that inebriate" since University and are a little rusty. I am gonna go find my physics text and brush the dust off it.

It would be good to understand this more and be able to make a change that causes two fundamentals to cancel each other out......

[marksman]

very interested in see where this goes
keep up the good work Jarhead

[Jarhead]

Paid off - $$$ is not what I meant.
I Meant with improved accuracy over all...

Sometimes I’ve noticed with trying to gain accuracy, you try different this, different that, and at times get results that don’t meet expectations. That’s all.

Gotcha, I am with you.

I will be pleased with better accuracy......but I will settle for learning, too.

I will keep posting as things progress

[mickb]

For big game rifles it was work up loads until I got velocity needed, no interest in group sizes, just get the scope zeroed and call it quits.

For pistol cartridges for lever actions I mucked around a bit more,I wanted a full power and subsonic load. For the subsonic load I'd be chasing something with less velocity spreads( since those small charges could vary velocity 10%) to ensure I had jackets expanding for every shot, and of course accuracy.

[Jarhead]

Thanks for the responses Bugman and mickb!

And for the good words TassieTiger & marksman!

[Tilb004]

I think about 40 rounds by the time I do 20 at various power charge then 20 at various seating depth .
Watch Erik cortina on chasing the lands on YouTube.
That's the way im doing mine now .

[Tilb004]

I think about 40 rounds by the time I do 20 at various power charge then 20 at various seating depth .
Watch Erik cortina on chasing the lands on YouTube.
That's the way im doing mine now .

[Larry]

Really I think it is something that is a continual process. At least once a year you should re evaluate many things when it comes to your shooting. I have found changes in the way you hold your rifle are very important likewise where it sits on you shoulder and just how much pressure you use to pull it back into your shoulder.
Your load will also vary over time to some extent more so if you initally have the bullet close to the lands as the lands or perhaps just one land wears and the jump becomes larger things will change. having one land wear more than others is also going to change things considerably.

Congratulations Jarhead being able to have an instrument that gives real data on this phenomenon is a game changer and will give great insight to the benifits of many myths and some real data to products such as barrel tuners to the point if they really do work and if so how they should be adjusted and not just tinkered with hoping to get better results. Real data is the only way forward and understanding all the things going on is the first step being able to quantify each of them is the second step.

[TassieTiger]

I’m impressed JH - there’s a lot more work and forethought in this than ppl realise...you’ve done well.
Re your muzzle exit - there are small, locking alloy boxes on eBay that might suit - I’ve made quite a few battery boxes / circuits in these things as they are openable and water proof.
https://www.ebay.com.au/itm/Aluminum-po ... 1103.m3021

[on_one_wheel]

Awesome work Jarhead!

I think your onto something very special.
I'd bet there's a solid market for what your developing.

Give it a year or two and your idea will be stolen and marketed by one of the big players if you don't get it patented asap

[TassieTiger]

^ was thinking same thing...wonder if Winchester or similar brand development have Something like this...

[Skinna]

They do now!!

Pretty amazing & fancy looking stuff from my perspective.

Hey what is it anyway?



Just kidding. Top stuff!

Hell im expending energy thinking of a small collapsible frame for a piece of 10mm thick steel to use as a gong & scratching my head lol.

[Jarhead]

Tassie.

Thanks for the info. I already have the 3D printer going on the design I posted though.....Its almost done. I will try to get the electronics install next week and aim to test it out on Sunday week.

Thanks for the good words one wheel!

[Jarhead]

Design to reality.....I love doing this stuff. The bullet exit sensor is together and working with an index finger through the beams- need to test it with a real projectile moving fast......
I'll give it a test at the range with the 22LR next and if it holds up to that.....I'll take some real measurements with the 6.5. Rippa!

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[Jarhead]

Another successful test day!

Verified that the bullet exit sensor is working- and then managed to capture both bullet exit and barrel elevation whip on the same trace! The top trace is the bullet sensor and the bottom one is the barrel angle sensor. They cross over at about 4.2 milliseconds and the barrell angle trace goes off the top of the scale. I can see that I am on the wrong part of the curve with that ammo and the target results reflected that- they were all strung vertically. It looked like I sawed the target in half down the middle.

Next step is to use the bullet sensor on the 6.5 to measure how the change in bullet exit time relates to muzzle velocity (i.e how many fps change makes the bullet exit time change by 1 millisecond). I'll do that the next time I am at hilltop after the magneto-speed arrives......

I also found it is painful to take a measurement without the rifle being clamped down as I move it when I get behind it to shoot. A very slight movement sends the trace off the display.

Can anyone recommend a portable way to clamp the rifle into position by the stock and keep it shoot able?

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[Larry]

Clamping the rifle may change all your results even more so how they pertain to real world shooting the rifle.
It looks like you have managed to make a device that can prove or disprove quite a few theories that have been out there such as OCW and OBT it will be very interesting if you can match up barrel position with the OBT predicted outcomes. I have as good as discarded it and just gone with getting the projectile to about the speed I want it to shoot at and then some tweaking mainly using seating depth to get the best on target result. The best and worst OBT really didn't show much difference at all.I think there is a lot more too the harmonics of a particular barrel on any given stock than just the MV and the time it takes to exit.

[marksman]

l agree that clamping the rifle may change all your results, l've seen similar change's in rifle's shot in lead sleds then shot without
or even how the rifle is held while shooting
l have not had much luck using other peoples OBT results but one thing l have seen is that once l find a sweet spot node in a rifle and work out the OBT in quickload l can reproduce that OBT with a different recipe in that rifle
your work is looking very good Jarhead

[Jarhead]

Hi Larry,

Agree there is alot more to harmonics than that. There are 3 that I am aware of and I understand how to get positive compensation from the first two. I don't have my head fully around arc yet.....

1. Barrel whip, which I am measuring above.
2. OBT- which I think of as "donut" expansion of the barrel from the breech to the muzzle and back. If the bullet exits as the crown contracts, good accuracy results.
3. ARC- caused by the barrel vibrating in a moment (i.e twist) as a result of the bullet accelerating into a spin when it hits the lands.

[Larry]

OBT is Optimum Barrel time it is all based on how long the projectile takes to exit the barrel. The person that derived the theory has worked out the times that he thinks the barrel will be in that top part of the barrel harmonic movement.

Marksman one of the big so called advantages of the OBT is that it can be transferred from one barrel to another. If the MV is the same then the barrel time will be the same. It should all work.

The barrel length will be the main factor in determining the resonant frequency but like I said I think there are many others factors that could influence this. For example just the profile has the barrel been fluted even to the point like are there any stickers on the barrel say cammo tape. Does the barrel touch the stock at any point. what type of stock it is fitted to and how it is attached.

Jarhead you may be thinking of the OCW optimum charge weight theory which to some extent should translate to similar results as the OBT weather the two actually do is something I have not been able to determine as the OCW is not a freely available piece of information. I think the author of the OCW thoery talks more about the donut expansion or at least uses it as an example of how a wave travels down a barrel and back.

I am starting to find from personal experience that certain projectiles have a sweet MV that presents the optimum accuracy that translates across barrels and different brands of rifles. However this still has flaws in it as I found that the loads work in barrels of different lengths which would be giving different MV throwing my theroy out the window and corresponding more in line with the OCW theory. There are factory loads that seem to work in all rifles of all sorts type and varying barrel lenghts that seem to give the best accuracy for shooters.

[Jarhead]

Larry,

OK- I hear you. I am going to read up about OBT and OCW again. I did previously research both on the same day and then enjoy some single malt scotch that evening so my brain cells may not have stored that info properly......

[Larry]

Its interesting stuff and theoretically it makes sense. But really nobody so far has been able to show definitely the process or how to correct it, (if it really exists) Your device could go a long way to actually show what happens as far as barrel movements and the cause of these from firing. There are certainly some phenomenons that have been shown to exist the effect been able to be measured and consistently been shown to be corrected for, One of those is simple muzzle jump. This was found to happen on cannons to rifles and in latter times each gun had a correction known and made to correct it.(Think of Artillery guns). On a riffle corrections are not so easy to work out and can only be found by testing trial and error. It can be shown to occur just using different weight bipods it is not necessary to hang weight on the barrel however that will also make a difference.

[TassieTiger]

Isn’t it amazing that there are still so many unanswered questions, so many potentials, in shooting a firearm consistently accurate...?

There are videos on YouTube of top end developers, locking down as many variables as possible, ie shooting inside 100m tunnels, ammunition locked down to nth degree, scientific bench rests that absorb recoil but return to exactly same place, temp, humidity...cleaning barrels every shot, etc etc etc just trying to control as much as possible - but even then, results are slightly variable for ?? reasoning...I just think that in itself is pretty darn cool.

[Apollo]

Isn’t it amazing that there are still so many unanswered questions, so many potentials, in shooting a firearm consistently accurate...?

There are videos on YouTube of top end developers, locking down as many variables as possible, ie shooting inside 100m tunnels, ammunition locked down to nth degree, scientific bench rests that absorb recoil but return to exactly same place, temp, humidity...cleaning barrels every shot, etc etc etc just trying to control as much as possible - but even then, results are slightly variable for ?? reasoning...I just think that in itself is pretty darn cool.

Been following this topic but really TT it isn't as hard as it seems. Yep fine, Jarhead is taking it to scientific extremes but really..?? As the topic was created it doesn't take all this extreme to tune "dial in" a rifle.

I've been shooting for decades and I am "OCD" as far as accuracy goes, but, I've done it my way with thought, some testing and tests.

Typically, I shoot at 500m in Benchrest Competition and for some years rated in the top dozen. Doesn't take much to fall in a heap either.

I'm always on the look for an idea to improve BUT... all the scientific / electronic ideas are fine but nothing beats on hand experience and trials.

Most of my firearms I'm very unhappy if they exceed 1/2 MOA and that isn't really hard to achieve if you approach the topic correctly. Other than Custom Built Target Rifles the rest of my collection is from Europe..ie Tikka & Sako. Well built and accurate. The others are expensive built Custom Rifles using USA Components...Accuracy, well less that 0.2 MOA if I have any chance to stay in the top 10 shooters at a national competition.

Boil it down, what Jarhead is doing to me is well over thinking...

[Jarhead]

The Magnetospeed arrived today (Woo-hoo!) so sometime this weekend I will have a crack at the next step- measuring the variation in bullet exit time to with respect to variations in velocity.

That figure is the last variable in a calculation that will solve for where on the curve the 6.5 should be to have positive compensation for POI changes due to velocity variation.

Then I can see if there multiple tangent lines available that match and try powder loads to those targets.

Here is my math scribble:

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I have another couple pages Tassie which has heat data- still a work in progress so I will save that one for now.