Barrel makers/rifle makers true barrel twist rate

[SamuelBerryhill308]

I was wondering what barrel makers and rifle makers barrel twist are really the twist rate that they are supposed to be l I guess this would be more towards factory rifles because I've never heard of a barrel blank maker messing up barrel twist rates but I guess it could happen.im asking this and I was looking at trying some heavier weight bullets and wanted to make sure the rifles I have would stabilize them so I check twist rate on my rifles with a cleaning rod and nylon brush and my christensen arms 300 win mag is 1/10.75 not 1/10 my winchester model 70 coyote light is 1/12.50 not 1/12 and my remington 700 sps tatical is 1/12.50 not 1/10 like is supposed to be.does these numbers sound normal? Now I'm thinking about rebarreling my remington even though it shoots well even with 175s but I'd like to try some heavy per caliber in it and I've got it set up for longer range stuff and would like to shoot heavier than 175s in it but I guess that idea is gone.i already bought a bunch of 210 vlds I guess I'll try them and see what happens. I guess ot comes down to what factory rifle brands barrels are what they say they should be?

 

[Tiny Tim]

That has not been my experience, at least not to those extremes. Are you certain your brush isn't slipping. Try again with a tightly patched jag and see if you get the same results.

 

[SamuelBerryhill308]

That has not been my experience, at least not to those extremes. Are you certain your brush isn't slipping. Try again with a tightly patched jag and see if you get the same results.

I'll try that and see if something different comes up this is just the way I was told how to do it years ago that's why I used a nylon brush

 

[BillLarson]

I believe factory barrels are mandrel hammer forged..... leaving zero tolerance for twist mistakes...
Custom barrels on the other hand are subject to whatever the operator sets machine up for.....
Gain twist rifleing is a whole nudder ballgame.....

 

[chav0_12]

Since your numbers are mostly close, I'd also ensure you're accounting for the chamber space as well. A 26" barrel from a manufacturers is going to be 26" from the end of the threads to the muzzle. So a 300 Win would have closer to 23" of usable twist in the barrel.

 

[Radman]

I was wondering what barrel makers and rifle makers barrel twist are really the twist rate that they are supposed to be l I guess this would be more towards factory rifles because I've never heard of a barrel blank maker messing up barrel twist rates but I guess it could happen.im asking this and I was looking at trying some heavier weight bullets and wanted to make sure the rifles I have would stabilize them so I check twist rate on my rifles with a cleaning rod and nylon brush and my christensen arms 300 win mag is 1/10.75 not 1/10 my winchester model 70 coyote light is 1/12.50 not 1/12 and my remington 700 sps tatical is 1/12.50 not 1/10 like is supposed to be.does these numbers sound normal? Now I'm thinking about rebarreling my remington even though it shoots well even with 175s but I'd like to try some heavy per caliber in it and I've got it set up for longer range stuff and would like to shoot heavier than 175s in it but I guess that idea is gone.i already bought a bunch of 210 vlds I guess I'll try them and see what happens. I guess ot comes down to what factory rifle brands barrels are what they say they should be?

I have only checked a few Savages using a mop but they were right-on.

 

[Hugnot]

I once had a PacNor 6.5-06. It should have been a 1-9. It would not shoot pointy 140 BTHP bullets well. Upon dragging a tight-fitting patch back thru the bore and measuring where a full turn occurred, I saw the barrel was almost a 1-10 twist. I believe that when button rifling a barrel, the barrel is rotated while the button is dragged thru the bore and the rotation rate might vary. Some of my button rifled barrels have slightly slower twist rates, like .125 or .25 inches more than marked on the barrel. As mentioned, a hammer forged barrel formed about a mandrel will have no variation.

 

[Mikecr]

Since your numbers are mostly close, I'd also ensure you're accounting for the chamber space as well. A 26" barrel from a manufacturers is going to be 26" from the end of the threads to the muzzle. So a 300 Win would have closer to 23" of usable twist in the barrel.

OP is concerned about twist RATE, not barrel LENGTH.

Cut rifled barrels are right on the money twist-wise.
There can be variance with the button rifling process,, +/- 1/2".

 

[JAYgs8163]

My guess is your process for checking twist rate is flawed since all three rifles you checked are off. Try this.

Make sure you wrap a patch around your brush/jag creating a firm fit in the barrel and you've moved the brush/jag about 3" into the rifling of the barrel, now mark your cleaning rod with a sharpie at the exact edge of where it's aligned with your bore guide. Now you need to mark with a Sharpie a index reference point also on the rod so you can see when the rod has made a complete revolution/twist. When you've reached that point of a complete revolution/twist stop and mark the rod again at the exact edge of where it's aligned with your bore guide. Remove the rod and measure between those 2 marks. This will give you a pretty exacting twist rate measurement. Being off a 1/16 of an inch or 1/8th of an inch on the revolution of the rod can equal a 1/2"-1" in your measurement of twist rate.

 

[Tiny Tim]

Since your numbers are mostly close, I'd also ensure you're accounting for the chamber space as well. A 26" barrel from a manufacturers is going to be 26" from the end of the threads to the muzzle. So a 300 Win would have closer to 23" of usable twist in the barrel.

Good point. One must ensure the mop/brush/patch is engaged fully in the rifling before beginning the measurement process. My experience with factory barrels have generally been within 0.125" on the twist rate. That being said, it's never been faster than stated.

 

[JAYgs8163]

Good point. One must ensure the mop/brush/patch is engaged fully in the rifling before beginning the measurement process. My experience with factory barrels have generally been within 0.125" on the twist rate. That being said, it's never been faster than stated.

Correct, hence the reasoning of getting jag/brush about 3" into the barrel and also having a firm, engaged fit.

 

[chav0_12]

OP is concerned about twist RATE, not barrel LENGTH.

Cut rifled barrels are right on the money twist-wise.
There can be variance with the button rifling process,, +/- 1/2".

Right, but a 3" chamber is included in the 26" barrel length. Meaning if you have a 1:10 twist it will have almost 1/3 less of a turn when calculating for 23" vs 26".

 

[JAYgs8163]

Right, but a 3" chamber is included in the 26" barrel length. Meaning if you have a 1:10 twist it will have almost 1/3 less of a turn when calculating for 23" vs 26".

The length of the barrel has no effect on calculating his twist rate. You only need a 10" section of barrel to calculate a twist rate of 1:10. The only time the length of the barrel comes into play is when the barrel is shorter than the stated twist rate. For instance checking twist rate in my MuzzleLoader could be a PITA as it's stated 1/22 but the barrel is only 20". So now you'd have to some math and reduce your ratios. In the case of measuring my Muzzy I would need to measure it as 1/2:11. 1/2 a revolution in 11". Anyways…..

 

[Fiftydriver]

I was wondering what barrel makers and rifle makers barrel twist are really the twist rate that they are supposed to be l I guess this would be more towards factory rifles because I've never heard of a barrel blank maker messing up barrel twist rates but I guess it could happen.im asking this and I was looking at trying some heavier weight bullets and wanted to make sure the rifles I have would stabilize them so I check twist rate on my rifles with a cleaning rod and nylon brush and my christensen arms 300 win mag is 1/10.75 not 1/10 my winchester model 70 coyote light is 1/12.50 not 1/12 and my remington 700 sps tatical is 1/12.50 not 1/10 like is supposed to be.does these numbers sound normal? Now I'm thinking about rebarreling my remington even though it shoots well even with 175s but I'd like to try some heavy per caliber in it and I've got it set up for longer range stuff and would like to shoot heavier than 175s in it but I guess that idea is gone.i already bought a bunch of 210 vlds I guess I'll try them and see what happens. I guess ot comes down to what factory rifle brands barrels are what they say they should be?

Most modern cut rifled barrels are pretty close to advertised numbers. Button pulled barrels will often be slightly slower twist then advertised simply because of the manufacturing process. in my experience a button pulled barrel will be around 0.2" slower then advertised twist rate.

when i started building my wildcat rifles for the public, we needed some custom barrels for the very heavy and long bullets we were using. was using a button pulled barrel manufacturer and had to order custom twist barrels for these new bullet designs. Since i had to pay for these custom BUTTONS i ordered them 1/4" faster twist then i wanted the end pitch to be, as such, they arrived for the most part dead on for twist rate.

as mentioned cut rifled barrels are usually dead on. Hammer forged barrels are also very close to the mandrel used to make the barrel. Now if the mandrel is actual accurate to whats advertised, hard to say….

i generally only use cut rifled barrels for these reasons. Also, i can get rifling to any pitch i want, usually without an additional cost, not possible with button pulled barrels.