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Air Gun Home Forum Index » General Air Gun Questions and Topics » How do the pro's choke a barrel????
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How do the pro's choke a barrel???? 
PostPosted: Tue Dec 18, 2007 6:54 pm Reply with quote
BBGun Bob
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Ok here it is . I have read many threads and backyard methods of how to choke a air rifle barrel.Someone said beat with a hammer(me never) another said to cut a nut in half and press it or squeeze it in a vice.yet somebody else said to put in a hydraulic tubing shrinker.To me this is like pulling a engine out of a car with a chainfall hooked to a dead tree limb.
I am just wondering how do the pro's do it? It seems to be top secret.There really can not be that much to it.For $40.00 you can have your barrel cut down as far as you want and have it choked and crowned.So in short ,,,this has to be a simple process or the cost be quite a bit more money.
MY QUESTION IS how do the pro's do it ?????? Its killing me.
And I'll bet the answer will not be found here either. Wanta Bet?? (just kidding)

Just a Stummper Question
From your Pal
BBGun Bob

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PostPosted: Tue Dec 18, 2007 7:12 pm Reply with quote
Alstone
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The way I have seen it done is in a machine somthing like a lathe, the barrel is held in a collet and the part to be choked is run beteen 3 roller blocks, the barrel is spun very fast and the roller blocks are moved up and down the barrel over the area needing the choke, at the same time the perssure is increased on the rollers, these rollers also have a very slight taper on them so as you get a nice lead in to the choke. The guy doing the job used a go and no go bore gauge to get the amount of choke he required. A fair amount of skill is required I should think.

Al

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PostPosted: Tue Dec 18, 2007 7:48 pm Reply with quote
2RCHA
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The same way they choke a chicken,,,,,,LOL,,,,,,I know,,Stupid,,But I had too, sorry. Apology , Andy.

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Thanks Al That sounds logical 
PostPosted: Wed Dec 19, 2007 6:04 pm Reply with quote
BBGun Bob
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Alstone wrote:
Al wrote
The way I have seen it done is in a machine somthing like a lathe, the barrel is held in a collet and the part to be choked is run beteen 3 roller blocks, the barrel is spun very fast and the roller blocks are moved up and down the barrel over the area needing the choke, at the same time the perssure is increased on the rollers, these rollers also have a very slight taper on them so as you get a nice lead in to the choke. The guy doing the job used a go and no go bore gauge to get the amount of choke he required. A fair amount of skill is required I should think.


Now I am sure this is how they do it! I have thought about doing this in a similar fashion.
My thought was to use a lathe and a large pipe cutter,but replace the cutter blade with another roller.I just don't think I could get enough pressure on the rollers to choke it.It is hard to squeeze something that thick and hard,but maybe with a cheater on the crank handle of the pipe cutter for leverage this could work.After all we're only talking a couple of thousands of an inch at most.I better start looking for a pipe cutter at a pawn shop or second hand store.
I have access to a lathe.
After the holidays I will have an extra barrel to mess with(for this experment).I'm going to send my .177 cal.Crosman Quest 1000X to Rich In Michigan and have him put a .20 Cal. barrel on it.
For some reason I like this caliber it seems to shoot very flat and has a lot FPE.That old Sheridan Pumper I'v been messing with is.20 Cal. and it will stack pellets from a shooting vice.

Thanks for the info AL
Now to put the thought in motion.
BBGun Bob

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PostPosted: Wed Dec 19, 2007 6:44 pm Reply with quote
Alstone
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Hi Bob
I think doing it the way you suggest would work OK, If you made it with a narrow roller, or somthing like a timkin roller bearing, you would get more pressure on a smaller area, you could also try heating the end of the barrel, provided the barrel is soft to start with.

Another way I have heard of is to plung the end of the barrel into liquid nitrogen, take it out and clamp a hefty coller around the end, when it returns to normal tempreture remove the clamp.
Sounds a bit iffy to me though.

Al

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No Control 
PostPosted: Wed Dec 19, 2007 9:32 pm Reply with quote
BBGun Bob
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Alstone wrote:
Hi Bob
I think doing it the way you suggest would work OK, If you made it with a narrow roller, or somthing like a timkin roller bearing, you would get more pressure on a smaller area, you could also try heating the end of the barrel, provided the barrel is soft to start with.

Another way I have heard of is to plung the end of the barrel into liquid nitrogen, take it out and clamp a hefty coller around the end, when it returns to normal tempreture remove the clamp.
Sounds a bit iffy to me though.

Al

Al ,
I am afraid by freezing the barrel and letting it warm up you may shrink it to much,you simply have no control over how much it shrinks.At least on a lathe you can stop and measure your progress if any.

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Re: No Control 
PostPosted: Wed Dec 19, 2007 11:26 pm Reply with quote
AirGunEric
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BBGun Bob wrote:
I am afraid by freezing the barrel and letting it warm up you may shrink it to much,you simply have no control over how much it shrinks.At least on a lathe you can stop and measure your progress if any.


I would be a bit dubious on using liquid nitrogen in such a case- who knows what quality of steel is used on a Chinese barrel and I would think the chances of fracturing it would be pretty high.

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PostPosted: Thu Dec 20, 2007 12:16 pm Reply with quote
Alstone
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Like I said "sounds a bit iffy to me", I would have thought there would be the possibility of the end cracking off. I gather the applicating was originaly used for shotguns.

Al

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How do the pro's choke a barrel???? 
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