Easiest way to determine twist rate?

[landcruzr]

Just what it says- what is the easiest way to determine the twist rate of a rifle? Is a cleaning rod with brush an accurate way?

[Mal H]

I've found that a tight patch works better than a brush. No matter which you use, be sure the brush or jag isn't unscrewing as you push it through the barrel.

[Swampghost]

You can get pretty close. Attach a brush, preferably just a bit oversized, to the rod. Pull the rod back until the bristles hit the bore and engage about 3/4". Make a mark at the top on the rod at a fixed point such as the back of the reciever. Pull the rod through until the mark is back at the top and measure the distance from your set point to the mark.

This will get you pretty close depending on how accurate YOU are.

[Kendo]

I'm not gettin the picture ,one more time please.

[Kendo]

No, really I'm not being a smart alec, I really dont understand. I've got a couple of guns I would like to check.

[jdscholer]

I've found that a tight patch works better than a brush. No matter which you use, be sure the brush or jag isn't unscrewing as you push it through the barrel.

I agree with Mal, a patch gets better traction for whatever reason. Get a good tight one started in your rifling and put a Sharpie mark on the side of your cleaning rod at the point where it enters the muzzle. Push the cleaning rod into the barrel until the rod has rotated once as gauged by another mark somewhere near the handle. Mark the rod again at the muzzle. Pull it back out and measure the distance between the marks. This is the distance you're after. jd

[alfack]

I think the easiest way is to google whatever gun you have and twist rate.

[Mal H]

Kendo, do you understand the process now with jdscholer's explanation?

What you are doing is determining the number of inches (X) the rod takes to make one complete revolution assuming the rod is following the grooves of the rifling fairly well due to the patch or brush pressing tightly in the grooves. That gives you the 1:X" twist rate.


alfack - that's not a totally reliable method. Many rifles of the same model were made with different twist rates. Not to mention that the barrel may have been replaced at some time.

A Ruger Mini-14 is a good example. It has come with twist rates varying from 1:10 to 1:8, maybe more.

[10 Spot Terminator]

The cleaning rod and brush method is ok in most situations but you need to know ther are a few "off the wall" twist rates out there such as 7 1/2 in., 9 1/4, 10 1/2 just to name a few. The cleaning rod needs to be a good one that the rod moves freely in not say one out of your dads vintage Outers cleaning kit . Start your brush or patched jag into the muzzle end of the barrel a few inches and then stop. Take a sharpie marker and directly against the muzzle make a mark accross the cleaning rod. Take the same sharpie and run it along the top of the rod making a long line on the 12:00 position for appx 18 inches. Now continue to push the rod into the barrell until the long line rotates back to the 12:00 position and again make a mark accross the rod directly in front of the muzzle. continue to push the rod through the barrel and then pull it back out just as if you were cleaning the bore. Measure the distance between the 2 lateral lines on the rod and you have the number of inches per one twist of the riflings in your gun .

[Kendo]

Yessir I do.I was makin it harder than it actually was. Thanks for checkin on me.

[Swampghost]

Just curious, how many of you clean from the muzzle? I was taught to clean from the breach whenever possible.

[Mal H]

Well, cleaning often during the lifetime of a barrel and checking the twist rate once are two different things. Yes, it's usually best to clean from the breach when possible, but when done carefully, even cleaning can be done from the muzzle without damaging a target crown. The choice of rods and jags is paramount though.

[Kendo]

I clean from either or both . I had never heard anything neg. either way until on here the other day. Whats the differance?

[Mal H]

We were simulposting, Kendo.

You don't want to nick the muzzle even the slightest bit because that can seriously affect a barrels inherent accuracy. You want the hyper-sonic gases escaping around the base of the bullet as it just leaves the muzzle to be as symmetrical as possible. A nick can disrupt that symmetry and upset the bullet ever-so-slightly. That's why cleaning from the breach is usually preferable, but it's not always possible due to the design of some firearms. Revolvers are a prime example of when you can't use a solid rod to clean from the breach. Some rifles are the same, for example, the Ruger 10/22 (although some folks, including me, have drilled a hole in the rear of the aluminum receiver to accommodate breach end cleaning.)

[Kendo]

Could this occur even with good brass cleanig rods? If so I could have a problem.

[Mal H]

Unlikely, but yes it could due to any contaminants on the rod itself.

Don't fret about it though, you would have to be exceptionally clumsy to damage a muzzle with any high quality cleaning rod. I say "high" quality instead of "good" quality because some would put aluminum rods in the good category. They're not due to the fact that when aluminum oxidizes over time it creates some very hard compounds - harder than steel. Corundum is a good example, with rubies and sapphires being the extreme. You're not going to find tiny sapphires on your Al cleaning rod, but you get the idea.

[Kendo]

I'll never clean from muzzle end again, I promise Lord if you would just let the target crown on my heavy bbl .308 be OK,Amen.

[btefft]

landcruzr,

The easiest way I know to determine the twist rate of a barrel is to insert a cleaning rod, with jag and patch (tighter the better), into the barrel. Wrap some electrical tape (any kind of tape will do) around the rod, making a "flag", say 12 inches out.

Hold a ruler up to the end of the barrel. Push the electrical tape "flag" in. Note the staring location of the flag, maybe it is up when you start.

Push the rod in. The flag will rotate as the rod travels along bore. If it takes 10 inches for the flag to return to the up position, then your twist rate in 1-10 (1 revolution in 10 inches).

That's how far the bullet travels along the barrel to make one revolution. Different weight bullets prefer different twist rates for optimum accuracy.

Hack

[zippy13]

If you don't like the idea of trusting a brush on a cleaning rod, there are alternate methods. The most accurate and complex, it to make a casting. Another way, is to use a simple wooden dowel that loosely fits your bore. You'll need a good light for this to work. On the tip of the dowel make a contrasting radial mark. Inset the dowel from the breech until it passes the chamber tooling and align the tip where the rifling starts. Holding that position, make a mark on the dowel at the muzzle intersection. Now, carefully observing the rifling and the tip of the dowel while drawing the dowel down the barrel. You'll be twisting the dowel so as to keep the radial reference always aligned with the same groove. When the radial mark does one complete revolution, stop! Now, see how much additional dowel is protruding from the muzzle measured in inches. This is your twist rate. To check, keep pulling and twisting to do complete a second revolution and stop. Now the amount of protruding dowel should have doubled. For each additional revolution of the reverence mark the protrusion should increase proportionally.

A point to remember: This and other methods are for uniformly cut rifling -- the twist remins constant for the full length of the barrel. Barrels have been cut with what's known as gain twist -- it gets tighter the closer you get to the muzzle.

[btefft]

Good point about the gain twist.

I'd think to see if one has one, they could use the cleaning rod method at the breech end of the barrel, and for comparison, do it again at the muzzle end.

Hack