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the .22's enemy..the wind

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04 January 2022, 06:22
Tesoro
the .22's enemy..the wind
This is an interesting ballistic tidbit that I didnt know for many years when I started shooting rimfire.Bullet drop is a constant so thats the easy one to account for.

Long Rifle Wind Deflection:
Those unfamiliar with smallbore rifle competition are often surprised to learn that target shooters almost universally use standard velocity ammunition in preference to the many varieties of high and hyper-velocity rounds available. The reason given is the low-velocity ammunitions resistance to wind deflection.
Despite what might seem at first to be the case, wind deflection is not proportional to the time of flight. Instead, it is proportional to the amount of delay in the flight caused by air resistance. The 1145 f.p.s. standard velocity .22 long rifle round takes .287 seconds to go 100 yds., but would take only .262 seconds to cover the same distance in a vacuum. The latter figure is easily found by dividing 300 ft. by the speed of the bullet (1145 f.p.s.), which would remain the same throughout its flight if it were in a vacuum. Thus the delay caused by air resistance is .025 second with the standard velocity ammunition.
The 1335 f.p.s. high velocity ammunition, which will take .259 second to cover 100 yds., would take only .225 second in a vacuum. Thus, the delay for this bullet is .035 second or 37% greater than that of the standard velocity round .22.
The high speed round, then, suffers about 37% more wind deflection than the standard velocity.
This remarkable result is due to the very rapid rate at which air resistance increases with increase in bullet speed in the region near the speed of sound. The .22 rimfires are the only important rifle cartridges that occupy this speed range, and they are the only ones that show more wind deflection as velocity is increased.
While air resistance always increases when the bullet is shot faster, the rate of this increase is less steep at supersonic velocities. Rifle bullets in general, contrary to the case of rimfires, are made less sensitive to the wind by raising their velocities.
NRA Firearms Fact Book
04 January 2022, 09:32
Cougarz
Just watch biathlon on tv sometime to see the effect wind has on a .22 rimfire bullet.


Roger
___________________________
I'm a trophy hunter - until something better comes along.

*we band of 45-70ers*
04 January 2022, 20:14
Tesoro
Just watch me shooting ground squirrels at 100 yds in the windy high desert!!
06 January 2022, 22:27
Peter
Sorry Tesoro, I d not understand this at all. Target quality 22lr ammo is always subsonic. Presumably this is because of projectile instability when transiting the sound barrier. BR50 competition died due to ammunition quality, or lack thereof.
There is a law of Physics that say that the resistance in a medium increases in proportion to the square of the velocity. There is no distinction as far as I know between below or above the speed of sound.
Peter


Be without fear in the face of your enemies. Be brave and upright, that God may love thee. Speak the truth always, even if it leads to your death. Safeguard the helpless and do no wrong;
19 April 2022, 22:39
Atkinson
Fortunately missing a rock chuck, p-dog, and such makes little difference to me..the 22 is a fun gun..I add or subtract a bit of Kintucky windage and cross my fingers, praise the red gods, and cuss the devil, before I shoot, sometimes it even works!! 2020


Ray Atkinson
Atkinson Hunting Adventures
10 Ward Lane,
Filer, Idaho, 83328
208-731-4120

rayatkinsonhunting@gmail.com