Naked Science Forum
General Science => General Science => Topic started by: neilep on 03/09/2007 00:13:28
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Hi Ya,
I'm orf with some peeps clay pigeon shooting next Saturday week . Never done it before.
These are some shotgun cartridges:
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Why do the pellets separate when in flight ?...do they not all follow the same trajectory ?...ie: they are shot out from a straight barrel aren't they ?
What's the science behind the change in direction ?
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This may not be the answer you are looking for, Neil. If we look at the forensics of shotgun wounds or spray, this gives you some idea of what the shot is doing in flight.
With a regular shotgun the hundreds of single pieces of shot effectively act as one mass, a single bullet if you like, at ranges of less than 4 feet you geta target hole of around 1 inch. 4 to 12 feet and the hole is about 2 inch, and beyond that the size of the hole is dependant on the choke, barrel length and size of shot.
The other thing to consider when looking at shotgun "spray" is the length of choke. The more choke the less the shot spreads. This is why sawn off shotguns have a much wider spread or spray pattern, they have no choke.
Choke - constriction of the barrel at the muzzel.
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The barrel has a finite width and the shot leaves the end over a (small) range of angles because the pellets all take different routes along it, bouncing against the sides.
The 'choke' has the effect of focusing the shot, reducing the above effect. I imaging that, if you fired a shotgun in space, once the shot had passed through the 'focal point', it would tend to diverge again. In air, it doesn't carry that far, however.
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This may not be the answer you are looking for, Neil. If we look at the forensics of shotgun wounds or spray, this gives you some idea of what the shot is doing in flight.
With a regular shotgun the hundreds of single pieces of shot effectively act as one mass, a single bullet if you like, at ranges of less than 4 feet you geta target hole of around 1 inch. 4 to 12 feet and the hole is about 2 inch, and beyond that the size of the hole is dependant on the choke, barrel length and size of shot.
The other thing to consider when looking at shotgun "spray" is the length of choke. The more choke the less the shot spreads. This is why sawn off shotguns have a much wider spread or spray pattern, they have no choke.
Choke - constriction of the barrel at the muzzel.
THANK YOU Paul....right at the last moment ewe cleared up for me what 'choke' was. I see what you're saying and am grateful for your reply !...Hopefully I should be able to hit some clay pigeons. Perhaps I'll have a better chance of hitting it the farther away it gets !
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The barrel has a finite width and the shot leaves the end over a (small) range of angles because the pellets all take different routes along it, bouncing against the sides.
The 'choke' has the effect of focusing the shot, reducing the above effect. I imaging that, if you fired a shotgun in space, once the shot had passed through the 'focal point', it would tend to diverge again. In air, it doesn't carry that far, however.
THANK YOU SOPHIECENTAUR.
I have learned a lot about gun chokes ! I came to the assumption that the shot pellets being tightly packed would act as a single entity. But it's clear from what you describe that shot pellets do exactly what they are designed to do.....separate when shot.
THANKS again.
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That is cool cause I always thought the casing must split open letting them spread so I was guessing and was wrong cool explanations Guys!
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If you think about it and look at a shotgun the cartridge case has a finite thicknes and the width of the charge is slightly smaller than the gun barrel so the shot has a bit of room to move as it goes down the barrel. It is possible to have a shotgun with a variable choke at the end so you can adjust the speread. The last thing you would want is for all the shot to clump together. occasionally this clumping happens and when it does the results are quite spectacular.
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This site gives some good information on shotgun ballistics.
http://www.pubmedcentral.nih.gov/pagerender.fcgi?artid=1238294&pageindex=1#page
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Cool Thanks paul!