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How come the barrel is this way?

 
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  #1  
Old 03-31-2011, 03:22 PM
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How come the barrel is this way?

I have a savage model 12 with a 26 inch barrel in.308 caliber. The twist rate for the barrel is 1 in 10. After cleaning the rifle the other day, I looked through the barrel just to see what it looks like. I wanted to see if it was clean. I noticed the rifling is the full length of the barrel. How is the twist a short distance and the rifling the whole length of the barrel? Seems to me, the rifling would only be 10 inches, since that's the twist rate. Who knows about this one?

Last edited by hatfield954; 03-31-2011 at 05:45 PM.
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  #2  
Old 03-31-2011, 03:42 PM
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Re: How come the barrel is this way?

The twist rate only indicates how many inches it takes for the rifling to make one full revolution.
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Old 03-31-2011, 05:56 PM
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Re: How come the barrel is this way?

onzah is right. The rifling in the barrel is cut, swaged, or some other method the full length of the barrel at a rate of 1 full turn in 10 inches. Faster twist rates would be 1 in 9 or one in 8. Slower rates would be 1 in 12 or 1 in 14, for example. The chamber is reamed and a very small area in front of the chamber is reamed straight at the groove diameter. That area is called freebore or leade and for your .308 it's about 0.11 inch tapering for about another 0.25 inch until lands are full height. The rest of the barrel retains the original rifling all the way to the muzzle.

-- gr8whyt
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Old 03-31-2011, 09:22 PM
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Re: How come the barrel is this way?

Quote:
Originally Posted by gr8whyt View Post
That area is called freebore or leade and for your .308 it's about 0.11 inch tapering for about another 0.25 inch until lands are full height. The rest of the barrel retains the original rifling all the way to the muzzle.

-- gr8whyt
gr8whyt, that's interesting with the leade tapering .011 for .025: Is there a formula for this? How do you figure the taper and length of taper?
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Old 03-31-2011, 09:54 PM
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Re: How come the barrel is this way?

So, in redthroat terms. You are telling me that the first 10 inches past the chamber has a tighter diameter than the rest of the length of the barrel. Am I correct on that gr8whyt?
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Old 03-31-2011, 10:48 PM
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Re: How come the barrel is this way?

You have a 26" 10 twist, 3"s of your barrel is chamber, so you have 2.3 complete twist and from the start of the rifling to the end of it at the muzzle there should be no more than .0005" difference in the lands and grooves.
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Old 04-01-2011, 01:59 AM
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Re: How come the barrel is this way?

Have any of you guys noticed that it's April 1?
You've been had ;-)
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