Checking Rate of Twist

[Jeff H]

I have read here a number of times where a fella has troubles using the recommended "tight patch" method and would like to contribute a suggestion.

Snug a patch eye up good in your cleaning rod an get a tight dry patch (not so tight that you cannot push it through without bending the rod) into the bore from the breach end and push it almost to the muzzle while gently rolling the rod between your first two fingers and thumb.  The "rolling" is just to make sure you follow the rifling and don't unscrew your rod tip (depending on whether you have a right or left-hand twist) or "trip" over the rifling - either of which will fool you regarding the twist rate.

With the rod hanging in the bore, take a 1 1/2" long piece of masking tape, hold it sticky side up and center it perpendicular to the bottom of the rod (6 o'clock) with the edge of the tape right up against the breach face.  Then wrap both sides UP equally around both sides of the rod and join the sticky faces at 12 o'clock, making a flage that sticks straight up.  You want the tape to be perpendicular so the two tabs you wrapped mate evenly along their edges.

Trim the top of the flag square with.....  OK you can skip the trim job.

Now, get ahold of the rod like you did pushing it in but start pulling it back out doing the same rolling bit to follow the rifling.  As you pull the rod out, the flag will begin to turn.  Stop pulling when the flag is again at 12 o'clock.

Then, measure from the breach face to the edge of the tape closest to the breach face.  If the edge of the tape clsoest to the breach face is 10" away, then your twist is 1:10.  You will likely be off a part of a degree with the flag, but not enough to mix up a 1:9 and 1:10.  If you peer across the edge of the flag as if it were a front sight, and align it roughly with your sights at start and finish positions, you could be even more accurate in your measurement.  You may not distinguish between a 1:9.5 and 1:10, but used in conjunction with dating and common twist rates for a particular brand/model, you will know what you have and it may be a bit easier than "doing the math" based on your barrel length.  You will eliminate any confusion you may harbor regarding how barrel length is measured on a given barrel and omit fractions of a turn in your calculation.

Jeff H

[quickdtoo]

Sorry Jeff, but a similar method is already listed in the FAQs under the twist rate chart, best jag to use is the type shown in the pic for full contact within the bore, and a rod with a ball bearing handle to allow the rod to follow the rifling.

Tim

http://www.gboreloaded.com/forums/index.php/topic,26264.msg141263.html#msg141263

[Jeff H]

Sorry Jeff, but a similar method is already listed in the FAQs under the twist rate chart, best jag to use is the type shown in the pic for full contact within the bore, and a rod with a ball bearing handle to allow the rod to follow the rifling.

Tim

http://www.gboreloaded.com/forums/index.php/topic,26264.msg141263.html#msg141263

Obviously not working for everyone, so I thought I would throw it in.  I have had my best luck with the "eye" or "loop"  and never felt it necessary to have a ball bearing rod if you feel your way along the rifling.

[quickdtoo]

Tight is the secret even if you have to add a paper shim(s) under the patch to make it tighter, the shallow rifling is hardest to check on the small bores. 

Tim