Home Forums Hunting & Shooting Long Range Hunting Need advice re 22lr - long range - super vs subsonics

Ok so for about 18 months I've caught the 22 Rimfire long range bug and been plinking out to 400 odd yards with my little CZ and 40g Solids - supersonics for the most part. Have also played with some 40g Subsonics but with my scope I can only get them out to about 330y before I run out of ele.

In both the super- and sub-sonic rounds I've shot lots of come-ups, and both check out with a BC of somewhere between .135 and .140. The only real difference I can discern is MV which runs about 1250 and 1050 fps respectively.

ANYWAY..... Why is it that with virtually identical BC, the supersonics with the far superior MV drift MORE in the wind? Doesn't shorter time in flight equal less wind drift?

I'm a relative novice with the LR shooting generally - it's a genuine query.

Strange things happen to a bullet when it goes transonic

Thanks Rock.

I don’t understand why though. I thought someone here might know...

Found this on another site a while ago ,

Nearly all standard velocity 22 Long Rifle ammo is subsonic from the muzzle, and thereby avoids any transonic issues entirely. This is one of the reasons most standard velocity ammo tends to be more accurate than High Velocity fodder. This is also why you almost never see supersonic High Velocity ammo used in smallbore matches. Nasty things happen when a bullet goes transonic, but as has already been pointed out here, some bullets handle this better than others.

Kevin Thomas
Lapua USA

Also

Lots of mystery surrounding transonic instability and how it limits range for some bullets.
One item not mentioned in the write up is the effect of altitude. At sea level, especially in cold weather, the list of bullets that are transonic stable is very short. On the other hand, get up to 5,000+ feet above sea level and almost all bullets are transonic stable due to reduced air density (plus they go a lot farther before slowing to transonic speed at high altitude).
-Bryan Litz

Interesting question. Too much for my head to handle. The speed of sound does drop with altitude:

https://www.fighter-planes.com/jetmach1.htm

So I guess at high altitude, the lower air resistance means the projectile doesn't lose speed as fast and takes longer to get to the (lower) transonic stage (assuming it started off supersonic) - compared with a projectile at sea level.

Thanks for the info gents. Yes it’s perhaps too much for my head too I think!

I’ve definitely observed that - all other things being equal - subsonics shoot more accurately in my 22 rifles. This includes at long range which I suspect is partially due to less wind drift and partly due to more inherent accuracy.

The simplest way I've seen it explained is that when the high velocity round slows down and goes transonic, it begins to wobble, which makes it less aerodynamic in flight. Those little 40 grain chunks of lead aren't very aerodynamic to begin with, so that wobble factor allows them to be affected more by wind than the standard velocity rounds, which never deviated from their flight path...

You will find that at distance, one of the most important factors in .22 LR ammo is the Velocity SD and ES. Minor velocity changes make a big difference in POI at 300 yards. The high end match .22LR fodder invariably has the lowest SD/ES. A semi-auto platform tends to increase velocity variances.

At 300 yards a 10 fps change in velocity equates to about 1.5 inches in elevation, depending on velocity and BC. While that might seem trivial, consider that the velocity spread of many 22LR high velocity rounds have extreme spreads in the 50-60 fps range and some brands can exceed 100 fps ES. Quality match ammo tends to run much lower, in the 15-25 fps range.

This extensive 22 ammo comparison at Accurate Shooter is a great resource. http://www.accurateshooter.com/guns-of-week/22lr-rimfire-ammo-comparison-test/

Grand I’ve been shooting out a little further with a new scope setup and what you say bears out.

Shooting at 380 yards, using better quality Subsonic ammo is resulting not only in less wind drift but also less vertical dispersion than the cheaper SuperSonics.

Hi-Vel bullets have to buck a significantly higher amount of drag, hence the cause for more drift. See the drag curve below.



Point being that if you will notice that drag increases a great deal from Mach .8 to 1.2, with the peak occurring near the velocity for HV ammo. BC may be approximately the same, but DRAG is not. Drift is mostly about drag rather than ToF.

Glad to hear it.

FYI the Ballistic AE Iphone App not includes velocity and BC data for many popular .22 LR rounds.

I remain(happily) in 40gr Federal AE Mode...beyond the 700yd line....................