Tunnel Testing 22lr With Some Surprising Data

[67rschev]

After reading Tim K's thread , I thought I would share some very interesting results from some testing that I did a couple of weeks ago . A fellow competitor was having a re-barrel of his match 40x that was finally done that we need to pick up out in the middle of nowhere USA . We then headed north another couple of hours to a private test tunnel owned bye a national level competitor that we had an open ended invitation to come stay and test . Plan was to shake down the new build and put a tune on it , as well as test my rifle with a couple lots of ammunition . [IMG2=JSON]{"data-align":"none","data-size":"full","src":"http:\/\/i768.photobucket.com\/albums\/xx323\/67rschev\/IMG_1498_zpsxb52tvwu.jpg"}[/IMG2]




Well the 40x with brand new Ratchet , went real sideways on us . Tried everything to get it to shoot for a few hours , he would be better off with a 200 dollar 10 / 22 it was that bad . We then got on to testing my Stiller Lonestar . The testing preformed was shot very similar to the KSS Eley Mobile facility . You take a cleaned gun , 10 sighters-foulers-scope adjustment , then 4 targets of exactly 25 individual bulls each ( ARA style and target ) . All shot consecutively with no cleaning in between , and held on the center dot . No adjustments in POA once started , was damn maddening not being able to hold over once started . No fixture for the action like the mobile lab , we were using an Arnold 1 piece roller rest so about as repeatable as possible . Now just as I started , a large storm cell rolled over . During the first two targets the humidity level jumped 50 points due to the downpour and temperature dropped 17 degrees in 20 minutes . Here are the compiled 25 bulls down to 1 screen shot in order target one to target four . [IMG2=JSON]{"data-align":"none","data-size":"full","src":"http:\/\/i768.photobucket.com\/albums\/xx323\/67rschev\/thumbnail_tdsT1_zpsaiiifjmx.jpg"}[/IMG2]
[IMG2=JSON]{"data-align":"none","data-size":"full","src":"http:\/\/i768.photobucket.com\/albums\/xx323\/67rschev\/thumbnail_tdsT2_zpshmmx2vyd.jpg"}[/IMG2]
[IMG2=JSON]{"data-align":"none","data-size":"full","src":"http:\/\/i768.photobucket.com\/albums\/xx323\/67rschev\/thumbnail_tdsT3_zpsy23feyet.jpg"}[/IMG2]
[IMG2=JSON]{"data-align":"none","data-size":"full","src":"http:\/\/i768.photobucket.com\/albums\/xx323\/67rschev\/thumbnail_tdsT4_zpsmjoddbx5.jpg"}[/IMG2]




It was very interesting to watch the first target fall apart on me whet the rain hit , and the second completely scatter with a major shift in ambient conditions . Although while shooting the targets I was more thinking that the ammunition choice may have been wrong , and the rig was shooting poorly . I always knew things such as temp and humidity played a role , but when shooting for score we are always shading / changing POA on the target due to conditional changes and fouling , so they never seemed as drastic . And then once the ambient conditions settled for target 3 and 4 , the gun settled and started to shoot this particular lot of Eley Black Match as it had preformed in the past .


For some more interesting data . Every shot was run over two chronographs and then was plotted on a graph with the POI compared to POA in relationship to speed . Here is the conglomerate of the 4 targets shot 1 to 4 , top to bottom . [IMG2=JSON]{"data-align":"none","data-size":"full","src":"http:\/\/i768.photobucket.com\/albums\/xx323\/67rschev\/thumbnail_Stat%20Summery_zpsjvuikw8x.jpg"}[/IMG2]




You might have to ramp up the magnification to read the graphs , best I could post of the screen shot . Some interesting things I noticed there . We all know how important ES and SD is , especially when we are at the mercy of the ammunition manufactures like we are when shooting rimfire . Its know fact ... blah blah blah ... that faster shots will vertically impact higher than slow . Overall you can see by the lines that this holds relatively true . But look closely , for example target 2 the one went scatter on me . The lowest impacting shoot , was dead nuts in the middle speed wise . Target 3 , the slowest shot was one of the top 5 highest impacting shots . I could go on and on looking at this data about the speed vs vertical point of impact . Also , the best target #4 had the worst SD and second worst ES , the second best target #3had the largest ES and second worst SD . Guess what I'm saying is there are many many more subtle things we deal with when shooting these silly guns that have a profound impact on what we see down range besides speed . From temp to humidity to barrel fouling to ignition condition all plays a role .

YMMV

 

[JG26_Irish]

67rscshev,

Maybe it is just me, but I could not see any of the pics you posted. Your post sounds very interesting.

Irish

 

[67rschev]

67rscshev,

Maybe it is just me, but I could not see any of the pics you posted. Your post sounds very interesting.

Irish

Hum , not sure comes up on both my tablet and PC . Is a Photobucket link will look into it . Here are the thumbs of the test data for now

 

[CMH]

Is the test tunnel open somehow or were you seeing such changes through the air handling system?

 

[67rschev]

Is the test tunnel open somehow or were you seeing such changes through the air handling system?

To answer your questions , no the structure is not open . Now the air handling system is not that sophisticated , actually the is none . I never ever felt the need for any system while the shooting was going on . Picture a large large shop that is maybe 70 bye 70 , and at one end a tunnel extends another 100 feet if you can kinda get the layout if you look at the picture I posted . You shoot from one end of the shop into the tunnel where at the other end there is a large trap , only 50 yards and rimfire only . Current conditions are measured bye two remote thermometers , of which one is placed half way down the tunnel , and what looked like a everyday digital weather station .

 

[jbell]

I have seen a known excellent shooting centerfire rifle go to hell when a big weather system was moving in rapidly. It was one of those days that you could feel the pressure change, like right before a tornado hits. The wind was not bad but the pressure was changing very fast. I never could figure out what happened, but always assumed the atmospherics were the cause. Interesting post!

 

[orkan]

This confirms two things that I've long seen but am still unable to explain. Some days, my rimfires just refuse to shoot. ... and I mean ALL of them. Rifles that I can go 90% on an ARA target pretty easily, struggling to get better than 30%. Just as jbell said, wind was nice and still, temperature was fine... but absolutely nothing shot well. I specifically drug out 6-7 rifles and several lots of ammo just to confirm it wasn't something wonky with a specific setup. They just refuse to shoot some days.

The second thing this confirms is that rounds of higher velocity can hit lower, and vice versa. I have long maintained this and seen this same effect with centerfires as well. (despite always getting shouted down by people) When tuning loads for my centerfires, I ignore velocity/es/sd completely. Once the load has been completely worked up, only then do I pull out the chrono and get some numbers so that firing solutions may be computed precisely. This has served me extremely well, as it seems to allow the rifle to cluster shots that shouldn't necessarily be clustered. It's interesting to see the exact same thing confirmed by your testing.

Great thread. Thanks.

 

[jbell]

The higher velocity that impacts lower on target may be explained by the bullet exiting the muzzle during the low or bottom of the barrel whip. We know barrels whip in a vertical plane when a round is fired. When we work up a load we strive to find the charge that allows the bullet to exit the muzzle during the dwell time (point of the whip when the barrel is not moving up or down because it is changing directions). So in theory the desired load will exit during the upper dwell as opposed to the lower, thus allowing the most accuracy and giving the highest starting point for the bullet to travel to the target netting the highest POI. -in theory-
But it is a scientific-ish explanation...

The weather thing creating poor accuracy, I like to pretend that never actually happens because it makes my head hurt to try and figure out what is going on.

 

[jbell]

But I have to say from my own personal experience most of the time higher velocity gives me a higher POI. Not saying it isn't possible, just that I have not really seen it much.

 

[The Mechanic]

Could it be falling in and out of a node? Maybe take the ammo and cool it in an ice chest or warm it up with a hand warmer and don't let it stay in the chamber for more than 20 seconds or so. Should be an easy test. May also give you some funny strings. Got a .22 that is SUPER sensitive to temperature. Bad barrel but just to lazy to change it.

 

[mikehotel]

.......When tuning loads for my centerfires, I ignore velocity/es/sd completely. Once the load has been completely worked up, only then do I pull out the chrono and get some numbers so that firing solutions may be computed precisely. This has served me extremely well, as it seems to allow the rifle to cluster shots that shouldn't necessarily be clustered. It's interesting to see the exact same thing confirmed by your testing.

Great thread. Thanks.

Hope this doesn't distract from the topic, but I'm glad you mentioned this. I recently purchased a Labradar , and if anything it added some head scratching because during load development my smallest groups doesn't always have the lowest numbers.

Thanks

 

[rg1911]

Hope this doesn't distract from the topic, but I'm glad you mentioned this. I recently purchased a Labradar , and if anything it added some head scratching because during load development my smallest groups doesn't always have the lowest numbers.

Thanks

What he said. It isn't uncommon for the best repeatable group to not have the best SD and ES. (Oehler 30P chrono.)

YMMV.

Richard

 

[Delicatessen]

Damn, for a minute I thought you were high speed wind tunnel testing...that would be an interesting set up in private use.

 

[67rschev]

Some great observations and points have been brought up

I think the POA vs POI in relationship to speed graphs have brought up many questions . I agree with you Jbell its math and physics , generally the faster the speed the higher the impact and the ' mean ' line shown in the charts prove that roughly .150 thousandths for this test , at this speed , at 50 yard . But the fun part of this wondering why if we look at any of the charts , and we pick the average speed there can be four shots at the same speed that impacted well over and under the median POI .

A far as tune on this piece , there is all kinds of fun garbage on this rig . Harrels , Pappas midbarrel , and a JJ slide ploob tube . Calfee would shit a brick , but have tuned several times and always wind up back to where they are set . We could get into ' Positive Compensation ' or ' Stopped Muzzle ' theory here , but not so much the point of the posting . I wanted to see more about what others thought about ambient conditions effect on rimfire , and for all not to be so quick to condemn and blame your ammunition for every dropped shot . May be one or many more variables at work here , and maybe some of that we can control .

 

[my human host]

This confirms two things that I've long seen but am still unable to explain. Some days, my rimfires just refuse to shoot. ... and I mean ALL of them. Rifles that I can go 90% on an ARA target pretty easily, struggling to get better than 30%. Just as jbell said, wind was nice and still, temperature was fine... but absolutely nothing shot well. I specifically drug out 6-7 rifles and several lots of ammo just to confirm it wasn't something wonky with a specific setup. They just refuse to shoot some days.

The second thing this confirms is that rounds of higher velocity can hit lower, and vice versa. I have long maintained this and seen this same effect with centerfires as well. (despite always getting shouted down by people) When tuning loads for my centerfires, I ignore velocity/es/sd completely. Once the load has been completely worked up, only then do I pull out the chrono and get some numbers so that firing solutions may be computed precisely. This has served me extremely well, as it seems to allow the rifle to cluster shots that shouldn't necessarily be clustered. It's interesting to see the exact same thing confirmed by your testing.

Great thread. Thanks.

Agreed. I normally wait until the load work is done before I clock a few rounds. An exception would be when wildcatting or perhaps messing with unusual barrel lengths.

 

[JG26_Irish]

The higher velocity that impacts lower on target may be explained by the bullet exiting the muzzle during the low or bottom of the barrel whip. We know barrels whip in a vertical plane when a round is fired. When we work up a load we strive to find the charge that allows the bullet to exit the muzzle during the dwell time (point of the whip when the barrel is not moving up or down because it is changing directions). So in theory the desired load will exit during the upper dwell as opposed to the lower, thus allowing the most accuracy and giving the highest starting point for the bullet to travel to the target netting the highest POI. -in theory-
But it is a scientific-ish explanation...

The weather thing creating poor accuracy, I like to pretend that never actually happens because it makes my head hurt to try and figure out what is going on.

Will limit my comments here to Rimfire since the centerfire world is a different animal. With Rimfire, we test ammo lots since we cannot work up our own loads. The goal being to find that velocity that best matches a Null in the bbl harmonic movements. It is conceivable to find a lot that at a given set of conditions will exit the muzzle during a period of relative stillness in theory producing the best accuracy in the given rifle. Now take that same rifle and raise or lower the temperature or atmospheric pressure or both and it is possible to find a proven combo that is all out of whack. A switch to slower or faster ammo of a different lot but same mfg will sometimes cause a gun that suddenly stopped shooting to be coaxed into once more performing as expected.

Using a muzzle tuner and lots of time and ammo, I once dialed in a Remington of mine into a ridiculous level of precision. Travelling to a local benchrest match I was ready to kick ass and take names only to be foiled by higher temps and lower pressures and some diabolical winds. These drove me nutz and I finished at a disappointing level down in the pack. Another day with same rifle but without the tuner, I took first place in the heavy factory rifle class and scored 3rd in the unlimited BR class narrowly missing 2nd place by results of one shot.

Without all the other variables, I have seen rolling wind vortexes travel down range when the wind blows from the shooters six at our local match range. It seems to be caused by the shape of the roof of the shelter (think airfoil). When I say "See" the wind, I mean the fluctuating movements of the dozens of wind flags in use during the more serious BR matches during these conditions. It only occurs when the wind is at our backs. This can disperse shots at 50y as much as 1/2" up or 1/2" down with the same rifle/ammo combo that was drilling the 10x out 30 sec sooner. Imagine a gust of wind that is rolling downrange just like a wagon wheel, Half way round and it is pushing the bullet down and another 1/2 rotation and it is pushing it up. If you shoot slo-mo video of these bullets, you will actually see the bullet porpoise up and down as it alternately passes thru these vortexes. The vertical POI dispersion opens up until the winds die down.

Irish

 

[orkan]

Irish, I've seen that affect as well. It doesn't only affect from the 6:00 position, but others as well if there are obstructions near where you are shooting. I have a lot of outbuildings at my place, and the wind does some very unpleasant things when coming from the direction of one of these buildings. Drastic vertical dispersion.

 

[justin amateur]

Tailwinds are fun. Rimfire results at 100 and 200 yards are laughable.

[IMG2=JSON]{"data-align":"none","data-size":"full","src":"https:\/\/lh3.googleusercontent.com\/1WW92DHBruZORmEMt2NUpjO9U0MmkmHUTl9ElP8jVFjuo6xtdGqlMyTcKm1gwc_NOSrhRZIuQbt6XA=w418-h177"}[/IMG2]

 

[Greg Langelius *]

Orkan: pull you 22s' barrels and chase the chambers with a 22LR chamber reamer, just handheld. Gets out the tiny ring of lead that ALWAYS forms at the very front of the chamber. Rifle will shoot like new after.

Do this periodically to maintain RF accuracy. This is not anything about weather patterns.

Fast, low, and slow, high are just variations in muzzle flip due to bore transit time deviations. All rifles recoil, some just do it small. Recoil force variations are negligible, bore transit time deviations are not.

Greg

 

[orkan]

Before jumping to conclusions about how well my rifles are maintained... don't you think a question regarding that would have been in order?

Suffice it to say, it had NOTHING to do with clean barrels/chambers or any other maintenance issue. When I take half a dozen rifles that were all producing .2-.5 groups on one day, and a few days later they ALL shoot 50% or more worse... it's pretty indicative that it's not an issue with the rifles/ammo. Swapping shooters made sure it wasn't shooter induced either. Then the very next day, all those same rifles are right back to shooting how I'm used to them shooting. Temperatures were virtually identical during all aforementioned days, yet it was clear that something was causing issues one day vs the next.

There is something to what is being said here in this thread about 22lr just refusing to shoot some days. I'm very interested in learning what the cause of this could be, and not very interested in relegating it to presently known and accepted theories. Thus far, none of those theories track with the facts.

 

[67rschev]

Orkan: pull you 22s' barrels and chase the chambers with a 22LR chamber reamer, just handheld. Gets out the tiny ring of lead that ALWAYS forms at the very front of the chamber. Rifle will shoot like new after.

Do this periodically to maintain RF accuracy. This is not anything about weather patterns.

Fast, low, and slow, high are just variations in muzzle flip due to bore transit time deviations. All rifles recoil, some just do it small. Recoil force variations are negligible, bore transit time deviations are not.

Greg

Maybe you could explain further ? ' Bore transit time deviations ' Sounds like the time the bullet is in the bore differences ? If two projectile clock the same exact speed can they spend different amounts of time in the bore ? I suppose one could accelerate to that speed faster maybe . And what could cause that , I would think outside forces that we are talking about in this thread . For this test , I am going out on a limb and saying it was quick humidity change . I have never had that much condensation in my tuner , ever . Water was literally dripping out of the end . Have recently changed loading style to have the breech / bolt open as little as possible between shots , I'd rather cook a round than leave the bolt open as my gun will wait for me . No discernible data , but It seems to may have helped .

Also , we scoped it before this session started , and only had the smallest hint of the carbon ring at 12 o'clock . After 100 rounds generally the carbon will stretch from 9 to 3 slowly building toward the bottom . Never an issue , and not to blame in this instance