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Measuring Twist?
Oct 23rd, 2018 at 5:22pm
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How do you go about measuring rifling twist in a gain-twist barrel?
  
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Re: Measuring Twist?
Reply #1 - Oct 24th, 2018 at 1:45am
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I'd like to hear other methods myself.
 
I used a degree wheel that's used for setting cam angle on an engine, a rod a little longer than twice the length of the barrel, with a needle attached to the rod for measuring degrees, wrapped the rod with masking tape and marked every inch - I cast a short plug of plastic and pinned it to the rod so as the barrel was moved up and down the rod, the rod was forced to turn.  I made a chart and plotted all the points corresponding with degrees.  With the help of Excel it gave a very clear twist rate per inch...   FWIW - it also showed that some button rifled barrels aren't always as consistent as we may believe, they stutter, they accelerate, a few are what they say they are -  the thrust bearing was in good shape?

I'd like to think there's an easier way but I can't visualize it.
Greg
  

"To invent, you need a good imagination and a pile of junk"  T. A. Edison
"If you don't know what leever A does, then leever B... you Dumb@$$"  G.C. Tryon
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