Posted on 05/14/2010 8:23:57 PM PDT by OneWingedShark
I was wondering about gun-smithing recently. Particularly rifling; I don’t know anything about the actualities of smithing, so it’s pure conjecture on my point.
Given a rifled barrel, they have constant rifling rates, is it possible to make ‘varying rate’ barrels.
Would such a varying rate reduce the wear on barrels?
To help clarify what I'm trying to get at, here are some pictures.
A constant rifling of 2 rotations per unit-length.
A variable rifling [ignore the negative portions] which starts at '0' {the rifling being parallel to the major axis of the barrel} to '8' which is the desired rate of spin to impart to the bullet. (with constant rate-of-change)
A variable rifling which changes at a varying rate-of-change, instead of a constant.
It’s called “gain twist.”
>It’s called “gain twist.”
Ah, I see... I’ve not heard of it before.
Guess it’s time to bounce to wikipeda and see the basics thereof. {Yes, wikipedia can be a bad source, but it’s generally a good starting point for a lot of non-political or technical stuff.}
The .460 smith and wesson magnum has a gain twist. There’s an article in a fairly recent American Rifleman about it.
Are short guns ever rifled?
Like handguns? Yes.
The rifling stabilizes the bullet. I’m not sure why you wouldn’t rifle any modern firearm, unless of course you had a projectile that was inherently stable. Maybe I’ll invent the football lace bullet.
Keep in mind that a bullet accellerates down the barrel. So even if you have a steady or constant rate of twist, the bullet will experience a progressive rate of twist due to it’s increasing velocity as it travels down the barrel.
I think some cap and ball revolvers were/are gain twist rifled, don’t know about rifles. Been in and out of fashion for years obviously. Possibly more applicable to slower velocities and/or heavier projectiles.
Bite your tongue and look up ‘progressive rifling’.
Not in any way associated with liberals/progressives in politics... LOL
There’s at least one specialty manufacturer that seems to use gain twist (aka progressive twist) rifling, here: http://www.sviguns.com/1201.php
The Italian Carcano had gain twist rifling. Nothing terribly wrong with it except it has a tendency to wallow out the groove in the bullet due to changing angle as it moves down the bore.
The advantage is the bullet originally hits the rifling as a slow twist which helps keep the bullet from deforming.
I have no idea why S&W chose it.
>Are short guns ever rifled?
Yes, Sometimes.
I saw a video where they were putting regular shot down one and comparing it to the normal scatter-patterns of a shotgun.
(It tended to make ‘O’ patterns.)
>>>Are short guns ever rifled?<<<
Ummm, Maybe when they get scraped for gonorrhea, maybe they spiral it.
Ok, sorry, couldn’t resist.......
>Bite your tongue and look up ‘progressive rifling’.
Why ‘bite my tongue’?
I was ignorant, knew my ignorance on the subject, and asked for knowledge.
gross
Sounds like a gimmick to me. Pointless.
Normally a BS monger in physics, luke actually gets one right. If anything, a slight “loss twist” might make sense if the thrust of propellant combustion gases falls as the projectile nears the muzzle.
I ‘Think’ that he was referring to the word: “progressive” in his post. (You know .. Progressives aka: Communists)
No need to get defensive.
And then you wonder why subsequent kids are screwed up.
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