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Old November 6, 2007, 02:09 PM   #1
Join Date: May 6, 2007
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Measuring twist rate

I've read about measuring your barrel twist. Can't remember where I read it or exactly what it said to do. Seems like I read about using a cleaning rod, making a small mark on it and when it comes back around make another mark and measure the distance between the two. How do you guys do it?
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Old November 6, 2007, 03:53 PM   #2
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Doing that has worked sometimes for me, but it is easier to just post the model of your firearm on a forum board, and someone will post the correct rifling twist. You can also e-mail your firearm's manufacturer and he will tell you.
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Old November 6, 2007, 03:56 PM   #3
Mal H
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That's the basic idea. I usually make a flag on the cleaning rod by putting a loop of tape (scotch, masking, etc.) on the rod. Then start a tight fitting cleaning cloth down the barrel until the flag is straight up. Make a mark on the bench at the front of the tape. Push the rod in until the flag is straight up again and make another mark. Measure between the two marks for the distance of one twist. (Actually, you don't have to make any marks on anything, just lay a yardstick next to the cleaning rod and note the distance that way.)

You can improvise any number of variations on the same procedure. Since twist rates are generally one turn in X.0 inches, you don't have to be real careful on the measurement. It will almost always be an even number of inches.

dodgestdshift - the problem with having someone else tell you the twist is that there are often multiple twist rates for the same firearm model. Different manufacturing dates, replaced barrels, etc. For example, if you ask what the twist rate is for a Mini-14 you could get 4 or 5 different, yet correct, answers.
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Old November 7, 2007, 01:12 PM   #4
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I know the twist rates on most of my rifles. I'm just wanting to find the twist for my AR-15. It was a custom build that recieved in a trade, so I will figure it out myself tonight.
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Old November 10, 2007, 10:21 AM   #5
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Measuring Twist Rate

This works for me:

Start a tight patch; being sure the jag is tight on the rod.
Mark the rod with a felt tip to indicate Top Dead Center and a starting point.
Advance the rod until it comes back to Top Dead Center.
Measure the distance traveled from the start mark. That is the rifling twist, one turn in xx inches.
A lot easier than trying to estimate the amount of twist in a foot.
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Old November 11, 2007, 12:42 PM   #6
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Be sure that the rifling is causing a tightening of your jag on the rod as you advance it.
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