Gain Twist Yay or Nay

[Aaron N]

So talking to my barrel guy he was suggesting using a gain twist in my Swede and 7x57 barrels.

are there any pros and cons?

 

[khesser]

I had one rifle with a gain twist barrel. Can’t say it shot better than other custom barrels I get from Bartlein or that it had improved barrel life. This was on a 6.5 Creedmoor. I don’t think there are any noticeable positives or negatives.

 

[Bob Nelson 35Whelen]

So talking to my barrel guy he was suggesting using a gain twist in my Swede and 7x57 barrels.

are there any pros and cons?

@Aaron N
Gain twist rifling has been around for a long time. The Italian carcano in 6.5x52 used it and a few manufacturers have used it over the years.
A mate had a sweede 6.5x55 built and the smith accidentally made a gain twist barrel instead of a normal. The mate had it fitted and gave it ago. Turned out to be the most accurate rifle he has ever used. Gain twist has its advantages but it has to be done PROPERLY.
The spin starts off slow and gets faster towards the muzzle end. Supposed to be easier in the projectile as well as reduce pressure as the projectile has a more gradual rotation until the muzzle. I can neither confirm or deny this as it's above my pay grade and mental capacity.
Try it and let us all know.
Bob

 

[Inline6]

I don't think it is required for the two cartridges you are building. Have used them in the past to try to make it easier on the bullets (pushing them hard).

I did not see anything negative. They all shot very accurately. That said, I like keeping things simple. I would run a fast twist and be done with it. If that is your only option for a faster twist or he has that on hand and keeps you from waiting a year for a blank. I would not hesitate.

 

[Aaron N]

Is it possible it would help prevent a 6.5x68 from being a barrel burner? From what I’m reading it’s easier on throats?

 

[khesser]

No. It won’t reduce barrel wear. I have found slower burning powders will help reduce barrel wear but not much else.

 

[Ontario Hunter]

Interesting thread. Thanks for posting. I'm learning something new and did not think it possible. Was sure I knew it all. So I was wrong. Another first.

 

[akriet]

Agree, interesting topic. I have read that the original Colt 1860 Army revolvers used gain twist.

 

[lockingblock]

Yes, but it’s not a game changer.

Accuracy issues come from twist that slows or is erratic. Gain is a way to get rid of those issues.

Bartlein does it best. I have a couple. They shoot as well as their other barrels, but no better.

Arguably, the ticket to a great barrel that’s intended for heavy for caliber (long) projectiles is a fast twist barrel with a slight gain.

My recipe for a 30 cal precision rifle barrel that will run 220-230gr match bullets is a 1-9 twist 5R. I might go to a gain twist that goes 1-9 to 1-8.5. It won’t hurt. Over stabilizing a bullet is not a bad thing in most cases.

 

[yamoon]

The man many believe the greatest barrel maker who ever lived, Harry Pope made gain twist barrels.

 

[Bob Nelson 35Whelen]

Is it possible it would help prevent a 6.5x68 from being a barrel burner? From what I’m reading it’s easier on throats?

@Aaron N
Alas it is not the bullet that erodes the throat it is the hot gasses that does that. The smaller the hole and the more powder the quicker it happens.
Depending on what you use the 8x68 for it should last you a lifetime of hunting. Start using it for a lot of little critters and you will burn it out real quick.
Bob

 

[Bob Nelson 35Whelen]

Interesting thread. Thanks for posting. I'm learning something new and did not think it possible. Was sure I knew it all. So I was wrong. Another first.

@Ontario Hunter
I'm finding the older I get the less I know, especially with this modern technology shit .
I even had to get my son to set up my phone so I could use it. My smart phone is smarter than me in a lot of things.
Bob

 

[Aaron N]

@Aaron N
Alas it is not the bullet that erodes the throat it is the hot gasses that does that. The smaller the hole and the more powder the quicker it happens.
Depending on what you use the 8x68 for it should last you a lifetime of hunting. Start using it for a lot of little critters and you will burn it out real quick.
Bob

But would lower starting pressures help with the gas issue?

 

[khesser]

But would lower starting pressures help with the gas issue?

Applied Ballistics has kind of tested this out in how twist rate affects muzzle velocity which would also factor in pressure. Faster twist rates have a negligible impact on velocity and to me that would also mean chamber pressure isn’t going to be much different from a slow to a fast twist barrel so a gain twist will not help in barrel life. Worth a listen.

How Muzzle Velocity is Affected by Twist Rate

Bryan and Mitch discuss how muzzle velocity is affected by twist rate and discuss what you need to know to make smart choices on this topic.

thescienceofaccuracy.com

 

[Bob Nelson 35Whelen]

But would lower starting pressures help with the gas issue?

@Aaron N
In my limited knowledge I would say no as you are still burning a lot of powder down a relatively small hole. Apparently some of the ball powders may help as the military showed longer barrel life in machine guns using ball instead of extruded.
Bob

 

[Inline6]

@Aaron N
In my limited knowledge I would say no as you are still burning a lot of powder down a relatively small hole. Apparently some of the ball powders may help as the military showed longer barrel life in machine guns using ball instead of extruded.
Bob

That my friend has more to do with the barrel than the powder, IMHO. Most machine gun barrels are chrome lined.

 

[Josh P]

My smart phone is smarter than me in a lot of things.

Find me a phone that can tune an Enfield and I’ll buy us one each.

 

[Ontario Hunter]

Find me a phone that can tune an Enfield and I’ll buy us one each.

Thirty years ago I would never have dreamed I could turn an 8mm Mauser into a 404 Jeffery. The internet made it possible. My phone didn't tune the action but it showed me where to find the information and parts needed to finish the project. A worldwide unlimited encyclopedia at my fingertips. Amazing.

 

[Bob Nelson 35Whelen]

Find me a phone that can tune an Enfield and I’ll buy us one each.

@Josh P
Enfields are easy to tune.
Bob

 

[Josh P]

Enfields are easy to tune.

Cause you’re not a phone, Bob.