Finding Twist Rate of the Rifling

[oldracer]

When I started with black powder, both cartridge and muzzle loader I kept hearing about twist rate and what to shoot with what twist rate? My mentor told me he made a measuring rod used just for that and here is what he did. Got a one piece of aluminum rod (long enough for any barrel you have), threaded the end so a patch holder could be put on it. I used a slight amount of epoxy to prevent coming loose. Since most barrels were 45 and 50 caliber one rod was all that was needed. There were several pieces of rubber tube on the rod so the aluminum would not run off in the barrel. The rod was measured from the tip of the patch holder in 1 inch increments and marked with a line straight down the rod and marks at each inch. Non removable ink or marker was used.

The first time I used it was to measure a Hawken kit I had assembled and did like this. Run the rod to the bottom of the barrel and put a piece of blue painter's tape at the muzzle end. Put several patches or enough so the rod was a tad hard to push in. Start at the bottom and pull the rod out and watch to see when the long line on the side of the rod makes one turn and count the number of inches it had to travel. If the barrel is a slow twist then measure a one half turn and so on. I record the numbers in my log book as many rifles have no markings.

I did not mention what to do if the measurement looks "strange". In this case measure at the breech, helps if breech plug is out and then measure from the muzzle to see what the readings look like. I bought an unmarked 45 caliber barrel and the twist rate appeared "strange". So I measured from both ends as the breech plug had not been installed for good. At the breech it was 1 in 20 and muzzle it was 1 in 15! The barrel was about 30 years old with no markings at all, but the rifling was like that of Pope and one or two other more modern barrel makers.
John

[bigted]

Only thing I would add is that instead of PULLING to measure, I always PUSH to measure.

I use the very same system tho and it always tells the facts. I always do three or four measurements to ensure a factual finding.

[LAGS]

I agree with the Pushing the rod into the barrel.
With most threads on the Patch Jag, if they are interchangeable, they sometimes Unscrew a little bit if you are pulling them thru a very tight bore.
Unless your barrel twists the opposite way of most barrels.
But on slow twist barrels, even 1:48 you are not going to get one full turn in the length of most barrels.
You have to do a little math to figure it out correctly.

[oldracer]

Thanks for the info guys, I added "I used a slight amount of epoxy to prevent coming loose." which I had forgot since when I was looking at the barrels the twist goes both ways and if the breech plug is off it makes no difference but I have had only one barrel that way.
John

[rfd]

a ramrod and a clothespin.

[LAGS]

Cloths pin.
Man you are as Ol' School as me

[rfd]

ain't rocket science.

[Winger Ed.]

I've done it with a good firm fitting bore brush on a spinning handle cleaning rod.

Get it started in the barrel, touch it with a Sharpie.
Pull/push it through slowly letting the rod rotate. When the mark makes one rotation, mark it again, and measure in between.

If you get something like 9 3/4 or 10 1/8, instead of a microscopically exact 10", you've got a one in 10 twist.

[indian joe]

ain't rocket science.

been wondering what all the fuss was about ---long hard winter in places I guess!

[LAGS]

Twist rate is a good basis for a Starting Point .
No matter what, You still have to Work Up your load.
There are so many factors that come into play.
And they don't always correspond to another rifle with the same twist Rate, Bore Size, and length of barrel.
But Checking one thing, like the Twist rate on your barrel is good.
That is one factor in the equation that will not change.
Your Projectile size, Projectile Hardness , powder load or even the primer or Patching will or can change.
I have seen Very Few guys on the firing line in any competition that were wearing a Hard Hat that said " NASA" on them.

[indian joe]

Twist rate is a good basis for a Starting Point .
No matter what, You still have to Work Up your load.
There are so many factors that come into play.
And they don't always correspond to another rifle with the same twist Rate, Bore Size, and length of barrel.
But Checking one thing, like the Twist rate on your barrel is good.
That is one factor in the equation that will not change.
Your Projectile size, Projectile Hardness , powder load or even the primer or Patching will or can change.
I have seen Very Few guys on the firing line in any competition that were wearing a Hard Hat that said " NASA" on them.

I should have clarified a bit I guess - checking twist rate to within about a half inch is easy with a ramrod and tight patch - seemed like we had a couple guys would not be satisfied with that level of accuracy which is what I kind of put down to cabin fever. (what is all the fuss about - I meant the difference from 19 to 20 inch is only gonna matter when you got everything else tweaked to the limit - anybody doing that will know ezxactly what twist they are shooting)

[oldracer]

I was watching a YouTube video a while back on barrel making with the new HAAS CNC machines and the guy showed how to set the rifling direction, depth, width and twist rate to 0.001 of an inch! These were hi power competition barrels I imagine and they need that kind of perfection, us on the other hand...…..
John