sub sonic .22 ammo

[vito]

Su-sonic 22LR works fine in my revolver, but not so fine in my Browning Buckmark. It seems it has less force to make the gun recycle properly. So mainly I have used sub-sonic in my S&W 617. FWIW, it doesn't sound any quieter to me than regular 22LR.

 

[B.L.E.]

Su-sonic 22LR works fine in my revolver, but not so fine in my Browning Buckmark. It seems it has less force to make the gun recycle properly. So mainly I have used sub-sonic in my S&W 617. FWIW, it doesn't sound any quieter to me than regular 22LR.

That's because hi velocity rounds are also subsonic out of a revolver. The noise is all muzzle blast in both cases.
It's the absence of the supersonic bullet "whip crack" noise that makes sub sonics so quiet out of rifles.
I was shooting CCI Quiet-22 rounds out of my 24 inch rifle and the people next to me thought I was dry firing.

 

[carguychris]

All things being equal, the longer a bullet (time of flight) is exposed to a cross wind the more it will drift off course. It's that simple.

Then why does a 1 ounce 12 gauge slug drift more than a sub sonic .22 LR? Is it because it's lighter?, no wait, 1 ounce = 437 grains.
Could it be because it slows down very rapidly?...

At 100 yards, it is still going faster than the standard velocity target .22 goes at the muzzle, therefore the time of flight has got to be less.

There's more to it than simple time of flight.

A 1oz 12ga slug has a much greater surface area than a .22LR bullet, so the same crosswind will exert a much greater force upon it. It's an apples to oranges comparison.

OTOH a 40gr .22LR HV solid vs. a 40gr .22LR SV solid is an apples to apples comparison. The bullet weights are the same. The bullet shapes are the same. The bullets' velocities will decay at the same relative rate. For the sake of argument, let's assume we're shooting them from the same rifle.

The only meaningful difference in terms of wind drift is that the HV bullet leaves the muzzle at a slightly higher speed and arrives at the target a bit sooner.

The longer the time that the bullet is exposed to the crosswind, the more the force exerted by the crosswind will affect the path of the bullet. It really is that simple.

A good way to understand wind drift is to change your perspective and define the air as stationary.

Now, instead of a stationary shooter shooting at a stationary target in a 15 mph cross wind, we have a shooter moving at 15 mph shooting at a target moving with him at 15 mph in a dead calm wind.

Let's put that target 100 yards away. The shooter is shooting across the deck of a big aircraft carrier that's 100 yards wide and steaming along at 15 mph in a dead calm wind. The motion of the ship makes the dead calm air feel like a 15 mph cross wind.
This air can't be drifting the bullet because it's a dead calm, all it can do is slow the bullet down.

The last statement is nonsense. If there is a crosswind, it will exert a sideways force against the bullet, and the bullet's lateral motion will be affected by that force. Period. It doesn't matter how the crosswind is induced.

For the sake of argument, let's pretend that you're a gunner in a B-17, and there's an Bf-109 fighter flying off your wing at the same airspeed and altitude as you. (The Luftwaffe pilot would have to be awfully stupid to do this, but I digress. )

To hit the Bf-109, you will have to lead it because you are firing into an apparent ~150 mph (or whatever) crosswind induced by the motion of the aircraft.

If you were on the ground shooting at a stationary target, using the same gun, in the same crosswind (which is admittedly unlikely), you would have to use the same windage correction as you would in the air. The crosswind is the same. The bullet's path is the same. The time that the bullet is exposed to the crosswind is the same. Thus, the amount that the bullet will drift is the same.

The more the air slows the bullet down, the later it arrives at the target and the more it hits behind the moving target.

For the sake of argument, let's pretend that the bullet has a little bitty rocket engine in it, and it therefore suffers zero velocity decay – it maintains 100% of its muzzle velocity all the way to the target.

Would you assert that such a bullet would not drift in a crosswind?

I would hope not. It would obviously drift.

 

[B.L.E.]

carguychris, if I'm so wrong, then please find a better way to derive the well known wind drift formula used by ballistics experts.

drift = wind velocity X (ta - tv)
ta is the actual time of flight
tv is what the time of flight would have been if shot in a vacuum

And while you're at it, please account for the fact that standard velocity .22 target ammo drifts less in the wind than high velocity ammo does. Ask any expert rimfire benchrest competitor.

Answering your last question, yes, if a rocket propelled projectile did not slow down on its way to the target, there would be zero wind drift, not only that, but if the rocket accelerated the bullet to a higher speed and the bullet arrived early, the bullet would experience negative wind drift. In other words, it would climb the wind.

But don't take my word for it, read what the experts have to say.
http://r.search.yahoo.com/_ylt=A0LE...DA317305/RK=0/RS=lwr3_Cp2ki6KUiay0ir5xawTtY0-

 

[4V50 Gary]

Don't expect it to work in a semi-pistol or rifle.

I saw one Buckmark that jam every now and then on subsonic 22 LR.

 

[B.L.E.]

My Smith and Wesson model 41 cycles just fine on CCI standard velocity ammo, but then, it is a target pistol.

 

[Sharkbite]

Don't expect it to work in a semi-pistol or rifle.

I have found a number of Subsonic loads (Rem, Fed, CCI, Gemtech) that function just fine in my 10/22 and 22/45.

 

[44 AMP]

Then why does a 1 ounce 12 gauge slug drift more than a sub sonic .22 LR? Is it because it's lighter?, no wait, 1 ounce = 437 grains.
Could it be because it slows down very rapidly?

Neither is the entire answer.

drift = wind velocity X (ta - tv)
ta is the actual time of flight
tv is what the time of flight would have been if shot in a vacuum

While I won't argue with the formula, I need to point out that the formula doesn't work "in a vacuum". MEANING that that formula ALONE is not enough.

Yes, velocity =time of flight, and it IS a factor, but it is ONLY a factor when comparing identical projectiles.

The 12ga slug drifts more than the .22, despite being a bit faster, for the same reason a three masted schooner with sails set moves faster than when all sails are furled and the masts are bare. There is simply many times the surface area for the wind to push against.

I won't comment on subsonic .22 drifting less than supersonic ones, as I have never personally witnessed this, and have not given the matter much thought.

It SEEMS this should not be the case, but I realize that not everything in the world behaves as it seems it should.

I simply almost never shoot subsonic or "standard velocity" .22s. The hi vel stuff I shoot clocked approx. 1250fps from 6" barrel handguns back when I was checking speeds.

 

[B.L.E.]

Let's go back to the Federal 1 oz slug data from the Federal website.

Federal one oz slug
Muzzle velocity 1610 fps
25 yard velocity 1467fps 10 mph wind drift 0.3 inches.
50 yard velocity 1340fps 10 mph wind drift 1.6 inches.
75 yard velocity 1229fps 10 mph wind drift 3.7 inches.
100 yard velocity 1139fps 10 mph wind drift 6.6 inches.

Tv is easy to calculate, it's the muzzle velocity divided by the distance. If shot in a vacuum, the slug would still be going 1610 fps after 100 yards and so the time it would need to go 100 yards (300 ft) is 300/1610 which is .1863 seconds.

Calculating actual time of flight from that velocity decrease can best be done by dividing the flight up into four parts and adding the times.
The first 25 yards it started off at 1610 and ended at 1467 for an average of 1535 fps and a time of flight of .04885 seconds.
From 25 yards to 50 yards it began at 1467 fps and ended at 1340 fps for an average of 1401 fps and a time of flight of .05355 seconds
From 50 to 75 yards it started at 1340 fps and finished at 1229 fps for an average of 1282 fps and a time of flight of .0585 seconds.
From 75 to 100 yards it started at 1229 fps and finished at 1139 fps for an average of 1182 fps and a time of flight of .0634 seconds.

Now we can estimate the actual time of flight by adding these four numbers.
.04885 + .05355 + .0585 + .0634 = .2243 seconds

So our Ta is .2243 seconds and our Tv is .1863 seconds.
Ta-Tv = .2243-.1863 = .038 seconds, in other words, the slug arrives at the target .038 seconds late due to velocity loss.

Now we have to figure out how far the wind moved during those .038 seconds.
10 mph = 176 inches per second
176 inches/sec X .038 sec = 6.688 inches. Remarkably close to the wind drift that Federal claimed. (6.6 inches)
Note that during that slug's .224 second time of flight, the air moved 39.4 inches.

Note also that I didn't have to know the bullet's BC, weight, shape etc. I got the wind drift just from the muzzle velocity and how fast it slowed down.

Actually, the formula does work in a vacuum. In a vacuum, the bullet does not slow down so Ta = Tv and (Ta-Tv) = 0. Thus drift in a vacuum is zero, no matter how fast the vacuum is moving. This agrees with our intuition.

 

[Erno86]

At the range...I find that the 22 subsonics, drift less in the wind than the high velocity 22's at 100 yards.