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slugging
Aug 5, 2016 18:43:55 GMT -7
via mobile
Post by firsttimecaller on Aug 5, 2016 18:43:55 GMT -7
I've picked up several contender barrels lately that I'd like to determine twist rate on. I have no lead handling equipment. How can I get some soft balls to do so. I have 17, 22, 25, 7mm and 45 to check or can I just use (j) bullets?
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Post by Bullshop on Aug 6, 2016 8:13:18 GMT -7
If all you want to do is to determine twist rate you wont need any lead slugs. The procedure I use to determine twist rate requires a cleaning rod and a tight fitting patch or brush. The tight patch/brush is inserted at the muzzle and with a permanent marker a mark is made on the top of the cleaning rod at the handle end and at the muzzle. The patch/brush is pushed into the barrel watching the mark at the top of the rod near the handle. When the mark makes one complete revolution another mark is made at the muzzle. Now with the cleaning rod removed from the barrel measure the distance between the two marks that were made at the muzzle. The distance between those two marks is the rate of twist of your barrel. This works best if you use a rod with a good swiveling handle but is not absolutely necessary. It can be done with a non swiveling handle if you apply a slight twist in the direction the rifling takes while feeding the cleaning rod. Most US made barrels are right hand twist but some Euro barrel or old milsurp barrels are left hand twist. It is good to know the direction of twist so that you can compensate for spin drift at long range. With modern high power cartridges spin drift can amount to about one minute of correction depending on the actual twist rate. Spin drift has been understood and dealt with for longer than most folks think. On the 1884 45-70 Trapdoor Springfield with Buffington rear sight the slider in the vertical sight staff is not vertical but is visibly canted to the left to compensate for spin drift of the 1/20" right hand twist rifling.
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slugging
Aug 6, 2016 10:24:22 GMT -7
via mobile
Post by firsttimecaller on Aug 6, 2016 10:24:22 GMT -7
Geez, thanks bullshop, First off I apologize for trying to think at 2am. And yes I've even used this cleaning jag method for other people. Good info for others though. Thanks again!
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