Transition To Subsonic (.22LR)

[JoeMartin]

Has anyone done any extensive testing on just how much a bullet (40 grain .22LR HV - 1240 to 1280 fps neighborhood) does transition when it goes subsonic?

What I'm wondering is if the end result at say 200 yards on an A21 200 yard NRA target - the transition has caused the bullet's path to wobble out then stabilize for an end result of 'x' amount of inches - be it 1 inch or more in any direction on the target when it strikes the A21 target?

Is it possible to come up with some sort of workable parameters that would allow a '10 Ring' consistancy with the use of a .22LR HV round shot from 200 yards even though we do not know which direction the transition to subsonic speed will move the bullet's path making the end result on the A21 target acceptable?

I'm thinking of doing some testing this Spring when I have better weather conditions.

Does anyone or is anyone using .22LR HV ammo with success right now at 200 yards, (staying within 1240 - 1280 fps)?

 

[RicSmith]

Re: Transition To Subsonic (.22LR)


I did this with the sierra 16 program for the cci round. I added wind just to see what it would do also. I was looking at trying the 200 yard also, I have shoot a lot of 100 yard matches with the but the 200 is somthing i would like to try, I use a win 52D with globe sights and am looking a getting scope mounts for it and trying something new. if you get any info on any of this please post it.






Trajectory for CCI Rimfire .22 LR 40 gr. Mini-Mag at 1235 Feet per Second
At an Elevation Angle of: 0 degrees
Ballistic Coefficients of: 0.13 0.13 0.13 0.13 0.13
Velocity Boundaries (Feet per Second) of: 1000 1000 1000 1000
Wind Direction is: 3.0 o'clock and a Wind Velocity of: 5.0 Miles per hour
Wind Components are (Miles per Hour): DownRange: 0.0 Cross Range: 5.0 Vertical: 0.0
The Firing Point speed of sound is: 1119.36 fps
The bullet drops below the speed of sound on the trajectory (1119.37 fps) at: 39 yards
Altitude: 235 Feet with a Standard Atmospheric Model.
Temperature: 59 F
Data Printed in English Units
Range(Yards) Velocity(Ft/Sec) Energy(Ft/Lbs) Bullet Path(inches) Bullet Path(1 MoA) Wind Drift(inches) Wind Drift(1 MoA) Time of Flight(Seconds)
0 1235 135.4 -0.1 0 0 0 0
25 1156.6 118.8 0.76 2.9 0.18 0.7 0.0628
50 1092.5 106 0 0 0.72 1.4 0.1296
75 1041.3 96.3 -2.58 -3.3 1.56 2 0.2
100 999 88.6 -7.16 -6.8 2.69 2.6 0.2735
125 962.7 82.3 -13.92 -10.6 4.08 3.1 0.35
150 930.9 76.9 -23.02 -14.7 5.71 3.6 0.4293
175 902.3 72.3 -34.63 -18.9 7.57 4.1 0.5112
200 876.1 68.2 -48.9 -23.4 9.65 4.6 0.5955

 

[TOP PREDATOR]

Re: Transition To Subsonic (.22LR)

JOE,

that's an interesting question, and the data ricsmith put up would be useful, though i think it would be better with a 0 mph wind entered, and adjust from that baseline.

if i understand correctly what you are asking, is it how much a bullet would "veer" off course once it goes sub sonic?

i'm not sure if it can actually be predicted as once it starts to destabilize and wobble, it may end up going in any direction (up, down, left, right)as it starts to wiggle through the air, plus i don't think a ballistic calculator anywhere would or could predict destabilization.

of course i could be completely wrong and the amount of wobble is a consistant thing that can be measured.....it may even be one of those things where you hafta somehow take out gravity (bullet drop) as a factor, to correctly predict the amount of "veering" as it's own entity, then compensate for drop. how to do that i don't have the foggiest clue.

i came up with a bunch of theories, however the end results came up with too many variables to be even a "scientific wild ass guess" (SWAG). the biggest speed bump being as the group opens up as distance is increased, which is negated all my other SWAGs.

i thought about comparing group size of hyper velocity rounds that stay supersonic at a certain distance, then find out where hv or sv rounds go sub sonic, and see what the difference is, but i don't believe the regular opening of the group is relative, so i scrapped them ideas.

i have a formula somewhere that "for every inch of barrel lost, using the same ammo, fps are reduced by _#_fps" that i thought may be useful by running those numbers vs. subsonic vs. supersonic at a set distance then measure the groups to come up with a SWAG of the "veering", but that got far fetched also.

that's a hell of a question, i'd think you'd almost have to shoot inside a 200 yard weightless vaccuum to get a accurate measurement; time to call MYTHBUSTERS

 

[Shiraz]

Re: Transition To Subsonic (.22LR)

With centerfire, the transition durring transonic flight causes the bullet to destabilize and to do unpredictable things hence the loss of accuracy.

With a centerfire round say the transonic/destabilized range is 1050 to 1125 yards. At this distance the bullet is totally unpredictable. If you increase the distance to target to say 1400 yards the bullet will restabilize and you can calibrate your sights and start getting hits durring subsonic flight.

With .22 rimfire the effects of transonic bullet destabilization are much less noticeable.

example
40 grain bullet
1250 MV
.130 BC
Sea-level
59 degree day

with the above data this example bullet goes transonic between 40 and 50 yards and is subsonic at 50 yards.

everyone has shot this and not noticed destabilization.

I'm not a physicist or much of a speller but here is my theory on transonic diffrences between centerfire and rimfire.

Centerfire bullets normally have a pointier nose which makes them bottom heavy. Once this bullet gets buffeted durring transonic flight the heavier tail causes the bullet to pitch and yaw. Also centerfire bullets, say a .308 175SMK has a length to width ratio of something like 3:1.

a rimfire bullet has less diffrence between its nose and tail weight so it is less likely to pitch and yaw. Also with a rimfire bullet the ratio of its length to width is closer to 1:1

Exit question, has anyone seen a .22 rimfire round keyhole in a paper target?

 

[TOP PREDATOR]

Re: Transition To Subsonic (.22LR)

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Shiraz</div><div class="ubbcode-body"> Exit question, has anyone seen a .22 rimfire round keyhole in a paper target?</div></div>

...damn shiraz, good point! maybe with the 1:1 ratio, i couldn't tell the difference, however i was never inclined to look for it, until now (well, spring time).

maybe shooting at several targets between that magical 38 yard to say maybe 58 yards (or wherever your particular ammo goes subsonic) would produce a noticable enough keyhole to be confirmed as destabilization, and if such a keyhole happens, make a group measurement directly before and after the "magical yard range" to see how much "veer" happened. once agin the usual opening of the group might screw that up, but at least it would be confined to a more specific distance with less amplified variables effecting the outcome.

generally i wouldn't worry about it and just stay with the sub sonic type ammo, but the transistion exists, and since it exists, it can be measured somehow.

either that or JOE is laughing his ass off watching us trying to figure out his 2010 riddle!

 

[JoeMartin]

Re: Transition To Subsonic (.22LR)

Hey, you guys have good information to share that's for sure!

Yes, this is a question on the up and up that I have been thinking about for a week or so and decided if anyone was going to be able to come up with the solution, it would have to be those here at SH that will figure out the answer.

If there is no answer to be had other then the unknown result at 200 yards, the answer may still be had if we are able to narrow down just how many inches of movement we have at transition?

The biggest obstacle we face is that we can not zero true at 200 yards with HV ammo within the 1240 - 1280 fps range (give or take on the FPS).

We could, if I'm thinking correctly take a page from those who have weighed and sorted their ammo into lots as a starting point and begin producing 200 yard groups on an A21 target with the different lots?

Next we would take the average size of each group/lot and perhaps determine what kind of pitch and yaw movement we have gotten, thereby giving us a rough idea of what we could expect?

I'm not a math wiz by any stretch, but I'm not sure pure math can answer this question without the field work to obtain only a table of probables that might occure within a combined total of given HV results.

Naturally weather conditions and wind would play a big part I'm thinking, so catching just the right day(s) to test is an obstacle in itself.

I will mention that the point of never seeing a keyholed .22 hole in the target is a very good point. I've never seen one at 200 yards but I've only shot subsonic at 200 yards on paper.

Now my mind is working overtime again...

 

[Shiraz]

Re: Transition To Subsonic (.22LR)

Joe,

At 200 yards all supersonic .22 rimfire ammo is at least 100 yards past transonic.(example a .130BC bullet at 1500MV[1,500!!!] at sealevel at 59 degrees F goes subsonic at 110 yards.)

So all bullets will stabilize at that point(200 yards) even if they are subsonic.

I don't understand why you can't zero with 1240-1280MV ammo?

I shoot with folks all the time who push HV ammo to 200+ yards. They have a flater trajectory but their MV inconsistancy causes their shots to string. Match ammo has better tolerances so the MV is more consistant

Something else is going on that transonic, I think

 

[JoeMartin]

Re: Transition To Subsonic (.22LR)

The reason I don't think it's possible to get a true zero at 200 with HV is when it goes transonic then settles to subsonic as there is no way of knowing for certain in which area (high - low - left or right) the bullet will strike as we are able to do with zeroing at say 25 yards where we know we should be able to get that 1/4 - 3/8 inch five shot group. (just saying as an example)

However, in contrast to the above, a zero with HV is possible at 200 yards if we're willing to give up a certain degree of accurcy that we still find exceptable at that range. Which does bring up the question, can we stay in the 10 Ring with HV ammo within the 1240 to 1280 fps range at 200 yards on a calm day?

Should we look at a stray '8 or 9 Ring counter' as a stray flyer or part of the accuracy of the bullets that may spread across the 10 Ring as I don't think each bullet would go subsonic at the very same point in flight since conditions in the barrel are changing with each shot.

If there is a formula/solution to be had for getting acceptable accuracy (or even true accuracy) from HV ammo at 200 yards, I just can't think of what it could be?

You mention,

"I shoot with folks all the time who push HV ammo to 200+ yards. They have a flater trajectory but their MV inconsistancy causes their shots to string."

Do they string with a consistancy in the same direction? If so, HV at 200 yards becomes very acceptable as one only needs read the stringing of the shots as they develop and then make windage or elevation ajustments with their point of aim.

Interesting thoughts for sure.

 

[Josh Smith]

Re: Transition To Subsonic (.22LR)

Hello,

My observations have been thus:

I have a 100 yard, life-sized steel spinner chipmunk or something of that nature. Chipmunk in size anyway. Probably a prairie dog.

With CCI Blazers, I can call my shots: Head or torso. All I have to compensate for is wind after I dial in the drop.

Risized and weighed ammo gives me just a touch more accuracy. Still, I hit 10/10 times on calm days, 7/10 times on windy days.

I figured maybe the subsonic would help with wind..

No joy - I hit the same regardless of whether the bullet starts out subsonic or supersonic.

At rimfire ranges, I just don't think it makes that much <span style="font-style: italic">practical</span> difference - not that I've observed anyway - and for longer ranges, I'll go with something a bit more powerful.

The best answer really is to just buy some subsonic, shoot it, then supersonic, shoot it. Draw your own conclusions from that.

Josh

 

[TOP PREDATOR]

Re: Transition To Subsonic (.22LR)

JOE,

just to clarify, so i'm understanding correctly, your "quest" is to find out how much of that adjustment is caused by the ammo hitting the transonic "wall" and a measurement of how much of that "veer" is ?

obviously if it's zeroed at 25 yards, and you shoot at 200, it's just a matter of adj windage and elevation for the difference of the POI, which is "x" amount of inches. this normal adjustment would be taking into account any veering that may occur, but not specific to the veering alone.

to throw into the mix, i would think that the amount of barrel twist (usually 1 in 16" for rimfires) and length would be a factor as far as stabilization goes, so one formula may not cover all types of rifles.

 

[JoeMartin]

Re: Transition To Subsonic (.22LR)

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TOP PREDATOR</div><div class="ubbcode-body">JOE,

just to clarify, so i'm understanding correctly, your "quest" is to find out how much of that adjustment is caused by the ammo hitting the transonic "wall" and a measurement of how much of that "veer" is ?

obviously if it's zeroed at 25 yards, and you shoot at 200, it's just a matter of adj windage and elevation for the difference of the POI, which is "x" amount of inches. this normal adjustment would be taking into account any veering that may occur, but not specific to the veering alone.

to throw into the mix, i would think that the amount of barrel twist (usually 1 in 16" for rimfires) and length would be a factor as far as stabilization goes, so one formula may not cover all types of rifles.
</div></div>

Yes... You summed it up exactly.

 

[Shiraz]

Re: Transition To Subsonic (.22LR)

Now I get it.
I don't think the 'veer' is mathmatically possible to predict bullet flight.

The only way to measure veer is group size, they get bigger.

I've shot centerfire out to a point where the bullets went transonic and when this happens you have no idea where they will go, some are high, some low, right, left.

for example we were hitting a 2foot gong with every shot, then backed up about 200 yards and the groups opend up to about a 12 foot wide and tall group


out past 150 yards or so you can really tell which ammo has a more consistant MV because of the vertical stringing.

but ultimately HV works out to 200+, groups will be bigger than subsonic match ammo

 

[steve_podleski]

Re: Transition To Subsonic (.22LR)

It's difficult enough for match ammo to consistently stay within the NRA smallbore 10-ring at 200yd let alone wasting time with HV ammo. I think that there is no 22lr ammo that can stay within the 10ring at 200yd for 20 shots. It's easier to shoot 1000yd centerfire matches than 200yd smallbore matches and it's not the inability to read the wind, it the ammo that's not up to the task.

 

[JoeMartin]

Re: Transition To Subsonic (.22LR)

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: stevepod</div><div class="ubbcode-body">It's difficult enough for match ammo to consistently stay within the NRA smallbore 10-ring at 200yd let alone wasting time with HV ammo. I think that there is no 22lr ammo that can stay within the 10ring at 200yd for 20 shots. It's easier to shoot 1000yd centerfire matches than 200yd smallbore matches and it's not the inability to read the wind, it the ammo that's not up to the task. </div></div>

There's some pretty accurate shooters here that'd probably say different about keeping 20 shots in the 10 Ring at 200 yards on an A21 Target, especially when they're using subsonic ammo.

I would agree that unless some extraordinary shooting was done with HV ammo,,, I doubt it could be done.

 

[Shiraz]

Re: Transition To Subsonic (.22LR)

How big is the 10 ring on an A21 target?

The name of the game for long range rimfire is ammo. Specifically consistantly or Muzzle Velocity.

At 200 yards, 30fps change in MV means a 2 inch change in POI.

In my experiance HV ammo works at distance because it does not seem to have transonic issues like centerfire.

I've chrony'd rimfire batches where the min/max spread is 100fps

 

[steve_podleski]

Re: Transition To Subsonic (.22LR)

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Joe Martin</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: stevepod</div><div class="ubbcode-body">It's difficult enough for match ammo to consistently stay within the NRA smallbore 10-ring at 200yd let alone wasting time with HV ammo. I think that there is no 22lr ammo that can stay within the 10ring at 200yd for 20 shots. It's easier to shoot 1000yd centerfire matches than 200yd smallbore matches and it's not the inability to read the wind, it the ammo that's not up to the task. </div></div>

There's some pretty accurate shooters here that'd probably say different about keeping 20 shots in the 10 Ring at 200 yards on an A21 Target, especially when they're using subsonic ammo.
... </div></div>I would like to see those groups posted...and not just the one lucky group but all groups shot that day.

 

[JoeMartin]

Re: Transition To Subsonic (.22LR)

Take a look in the November results posted here;

http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=1528683#Post1528683

You can also look through the other monthly results at the above link for scores.

 

[Hellbender]

Re: Transition To Subsonic (.22LR)

The muzzle velocity variation will far overshadow any transonic shift at 200 yards with the low B.C. of .22 bullets.

The transonic shift will happen between 40-65 yards and will show up on a 100 yard target just as easily. All it does is open group size, there's no magic 1" left or down or whatever when it happens.

Here's a 400 yard group I can duplicate about anytime with no wind, the MV variation with this ammo is approx. 40 fps, (Am. Eagle HV Lead) it measures about 4" x 12" tall, 9 of them are in about 2.75" vertical. Takes 64.5 SMOA adjustment on the scope to get there....