Smooth Twist Rifling!

L

l98ster

New member
Hi everyone,

I was just watching a youtube video produced by airguns of Arizona that was featuring a rather expensive airgun that used a "smooth twist" rifling system.

According to the presenter, the 24" barrel is smooth bore right up until the last couple of inches, which then has an "aggressive" twist. The idea behind it is that it allows the pellet to build as much speed as possible, and then at the last second, hits the rifling and begins to spin.

My question is for the people that are a little more physics savy than I. I understand that the pellet (.30 caliber @ 870fps) was moving slower than a traditional bullet, but can this technology be adapted to a firearm.

Thoughts????

-George
 
It kinda sorta was a while back.
There was a system with very long twist at the breech that progressively tightened up as you went towards the muzzle.
It was called "Gain Twist Rifling".

For shotguns there was a smoothbore to rifled bore called "Paradox" as well I don't recall it being any better than regular rifling & its rare or extinct nowadays. I've heard of rifled chokes on smooth bores as well.
 
S&W uses gain twist rifling in their long-barreled .460XVR revolvers. It starts the bullet spinning relatively slow at the beginning of the barrel and speeds up as it gets closer to the muzzle.
 
Interesting concept. Someone could make a 2-part barrel. The first part would be nothing but a very hard chrome-lined smooth bore, and the second part with rifling could screw into the smooth-bore. It sure would be easier than swapping out barrels with the rifling starts to wear or the crown gets dinged up.....if it would work.
 
Thing is, a firearm has a lot more gas volume and pressure available than a pellet gun. It does not need a launch section.

The Skans System could probably be made to work, but the required precision of alignment might make it just as expensive as replacing a whole barrel.
 
The problem I see is that if the bullet reaches much velocity before it inters the rifling of the rifle it would damage the bullet as is skids into the rifling.

I want my bullets to start the "spin" as soon as possible before they gain velocity.
 
Was it really .30cal at 870fps or was that a typo?

Depending on bullet weight...
That sounds like a VERY capable airgun. By caliber and velocity, that exceeds old school .32cal revolver rounds like .32 S&W and seems to be in the arena of a .32 ACP pistol.
 
kraigwy said:
The problem I see is that if the bullet reaches much velocity before it inters the rifling of the rifle it would damage the bullet as is skids into the rifling.

I want my bullets to start the "spin" as soon as possible before they gain velocity.
Click to expand...
I agree. Having the projectile reach maximum velocity before slamming into the rifling sounds to me like a recipe for poor accuracy and very short barrel life.
 
This sounds a lot like the Paradox barrels that Ross Seyfreid wrote about that had rifling at the end of the barrel and would shoot shot shells and pattern well but would also give good accuracy well slugs loaded in shotshells.

Gain twist rifling is an old idea. It seems like I have read about it being used in early black powder rifles and I believe one version of the Carcano rifle also used it.

You use to be able to buy shotgun tubes that were rifled so you could shoot slugs for deer hunting from your smooth bored shotgun and still get a stablelized solid projectile. They may still be available along with the proper slug loads for them. This is not a new idea.
 
The myth of a shotgun rifled choke improving accuracy is just that - myth. I've never seen any documented evidence that they improve accuracy over a smooth bore with a good quality foster slug that is matched to that barrel.
 
It kinda sorta was a while back.
There was a system with very long twist at the breech that progressively tightened up as you went towards the muzzle.
It was called "Gain Twist Rifling
Click to expand...

My S&W Sport has gain twist.
 
This sounds a lot like shotgun rifled chokes. They have been around since they started putting removable chokes in shotguns.

See this link about a test of one.

http://www.guns.com/2012/07/11/do-rifled-choke-tubes-improve-slug-accuracy/

Of the many technological developments intended to improve the accuracy potential of shotgun slugs and also one of the most summarily dismissed is the rifled choke tube. After all, claim the device’s critics, how could a few inches of shallow rifling at the end of a smooth barrel do anything to tighten slug groups? Further, won’t the fact that that the slug is engaging the rifling only after reaching near-peak velocity actually be detrimental to accuracy?
 
The myth of a shotgun rifled choke improving accuracy is just that - myth. I've never seen any documented evidence that they improve accuracy over a smooth bore with a good quality foster slug that is matched to that barrel.
Click to expand...

Do a little research and you will find a lot of documented proof that rifled chokes and fully rifled barrels gave great slug accuracy. like 3" and less groups at 100 yards. And no, not with that goofy Foster slug but with a slug designed for a rifled choke or rifled barrel. The gun mags had many articles 15-20 years ago with test using Brenneke and other slugs. Some were from Remington IIRC. So yes slugs can be made to shoot from a rifled choke.

Here ya go. Read about the remington slugger loads at the end of the test.

http://www.guns.com/2012/07/11/do-rifled-choke-tubes-improve-slug-accuracy/
 
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