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Hot Topic (More than 10 Replies) 22 shorts again (Read 11671 times)
Schutzenbob
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Re: 22 shorts again
Reply #15 - Feb 26th, 2009 at 12:09pm
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Friend Waterman,

I have an old beat up 3rd Model Winder which when I bought it years ago had the original 22 Short barrel which is not in the best of condition and was, at some time in the past, re-chambered to "22 Long R" probably by R. F. Sedgley, and to add insult to injury it has a ring in the middle of it. Now, regardless of the barrel's less than perfect condition, using CCI 22 Short Target ammo, I shot a 25 yard 10 shot group that I could cover with the tip of my little finger, as I recall I was using a Lyman 438 scope. At that point I stopped looking for 22 Short ammo and stocked up on the CCI Short Target.

Bob

PS I have had very bad luck with the Aguila Golden Eagle Target ammo.
  
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waterman
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Re: 22 shorts again
Reply #16 - Feb 26th, 2009 at 2:00pm
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Bob,

I was in the midst of such a test from the bench, using the Wyoming Schuetzen Union gallery target at 25 yards, when very heavy rain stopped the test.  I was sighted in and had begun to punch the 25-ring on a couple of targets when the rain came.  So the test's partial results before rain were very similar to yours.  I was using iron sights, a 17A with Lee Shaver  cross-hair insert in front and a Lee Shaver Mid-Range Soule as a tang sight.

I'm an hydrologist by profession and I have 40+ years of measuring rainfall intensity.  The rain squall that hit was delivering water at an intensity in excess of 2 inches per hour.  (That's the point when most folks turn the wipers to the highest speed, but far less than the cow and flat rock scenario.)  

It occurred to me that I had a perfect setup to test the effect of raindrop impact on a bullet.  I only got off 3 shots before the rain squall let up, but each of the three shots hit 3 inches below the center of the bull I aimed at.  There was some horizontal dispersal, with bullets hitting to the left, but the vertical displacement was pretty uniform.  

So here's a point for discussion:  How many raindrops hit each bullet?  Assume that a raindrop has the same volume and diameter as a 1/4" sphere and that there was a uniform distribution of raindrops.  IIRC, CCI Target Shorts have an advertised MV of 760 fps.

Richard aka waterman
  
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Schutzenbob
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Re: 22 shorts again
Reply #17 - Feb 26th, 2009 at 2:32pm
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Richard,

I'm about to leave to go shooting at "Windy Acres Gun Club," unfortunatly, we don't get enough rain out here to conduct a proper deflection test, perhaps Joe "Westerner" or some of his buds from the Pacific Northwest could figure it out, I did want to say that Midway has a sale on 22 Ammunition and has the best prices I've seen recently. Such is life in the far west.

Bob
  
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chrisj
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Re: 22 shorts again
Reply #18 - Feb 26th, 2009 at 3:06pm
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Waterman

Was that 3 inches due to raindrop impact or to the downdraft due to the rainfall?  3 inches seems like a lot in 25 yards for just wind though.

I'm thinking the effect has to be in slowing the bullet or the wind rather than deflection, since the shots were all uniformly down, and deflection could be any direction.

Just thinking.

Now back to working on drainage.

ChrisJ.
  
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marlinguy
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Re: 22 shorts again
Reply #19 - Feb 26th, 2009 at 8:00pm
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If it was caused by deflection, then why would it be 3" low? Some of those drops had to be hitting the underside of the bullet nose, which would have driven the bullet upwards. Something going on with all shots being 3" low.
  

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Richardwv
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Re: 22 shorts again
Reply #20 - Mar 1st, 2009 at 6:19pm
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The terminal velocity of raindrops varies by the size of the drop, but assuming larger ones (which a heavy rain would contain a significant portion of), the average velocity would be about 24fps....screaming for a raindrop, but sort of standing still compared to a bullet.  While rain  has at least 3 methods of affecting a bullet (deflection from downward force of the drop, deflection from downdraft and resistance to forward movement), it is the later one that would seem to result in the most consistant effect over a string of shots....and in reality is more of the bullet hitting a drop of water rather than a drop of water hitting a bullet.

So here is one for the experimenters out there.  Shelter a chronograph at say 100 feet and shoot under various rain scenarios (including no rain) and see what the affect is.
  
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waterman
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Re: 22 shorts again
Reply #21 - Mar 3rd, 2009 at 1:16pm
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For the raindrop to impact the bottom of the bullet, the bullet would have to hit the raindrop.  Raindrops are "raindrop" shaped, so if the bottom of the bullet hit the raindrop, it would only hit the tapered upper end of a downward moving mass. 

Assume a velocity of 750 fps for the 22 Short bullet.  Ignore deceleration (since I can't deal with it) and we have a time of flight over 25 yards of 0.1 seconds.

The bullet can hit any raindrop (or vice versa) within a path that is one bullet diameter plus one-half a uniform raindrop diameter on either side of the bullet.  With big uniform raindrops, that diameter is .25".  So the path width is 0.47"

With a steady one-hour rain dropping 2" of rain, a path 75 feet (900 inches) long x 0.47" wide will be hit by 110,122 raindrops in one hour.  Neglecting gravitational acceleration, bullet deceleration, bullet spin (450 revs per second) and the bullet trajectory (all beyond my elderly math skills), the bullet will be hit by (or will hit) 3 raindrops on its path to the target.

I think that is enough to deflect the bullet, but would the deflection be 3 inches?  Without getting into vectors, and again, I have fuzzy math skills, if a single raindrop with a downward velocity of 24 fps hits a bullet with a velocity of 750 fps, the result can be thought of a change in direction and can be thought of as a tangent function.  The arc tangent of 24/750 is one degree and 50 minutes.  If the raindrop was a solid of the same density as the bullet and if the bullet was not spinning, the bullet would be deflected by almost 2 degrees, or 27" at 25 yards.  Since the raindrop is much less dense and since the bullet is spinning, the deflection will be much less.  But I think I can believe a 3" deflection, especially if we include the downdraft factor.

Downdraft must also be a factor.  As must the angle between the rifle barrel and the target.  I made no effort to correct for that angle, which could well have been negative.  I often staple 3 targets in a vertical column.

Richard
  
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