Rifling

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Rifling Strelok 08/25/18 (Sat) 18:11:20 d0fa4c No.604041

In this thread: We will discuss if it's better to keep barrels rifled or to start rifling bullets themselves. Which one is cheaper? more effective? Why does the atf hate smooth barrel firearms? etc.

Strelok 08/25/18 (Sat) 18:33:16 16dfa7 No.604045

Surprise: foster slug rifling isn't to spin the slug in a smoothboore, its to provide space for swaging through smaller bores and especially chokes without damaging the barrel, the idea more to have the hollow core and cut "rifling" in the slug to hopefully expand to the bore much like a hollow base lead rifle or pistol bullet. Its more of a shuttlecock than anything else.

Rifling bullets doens't work, the spin rifles impart to bullets comes from the bullet actually spinning the bullet as the lands cut into the bullet as its being violently pushed through the barrel, its not the wind spinning the bullet as it passes over the rifle cuts in the bullet.

Also barrel obturation is extremely important, a rifled bullet down a smooth bore would allow for gas and pressure blowby losing pressure and creating incomplete dirty burning of powder. Especially if you make the smooth bore the size of the raised part of the rifled bullet. If you built the bore to the size of the smaller part it would simply swage the bullet into a smooth uniform shape again anyway.

Strelok 08/25/18 (Sat) 18:34:30 162a2b No.604046

The grooves on "rifled" slugs do not impart any spin to the projectile, they're just there so the slug can more easily swage itself through a choke.

Strelok 08/25/18 (Sat) 18:38:12 94c47e No.604047

How do you seal a bullet to the barrel if the bullet is rifled but the barrel isn't?

Strelok 08/25/18 (Sat) 18:53:27 e1ae05 No.604048

>>604041

lmao OP has no idea how rifling works

Strelok 08/26/18 (Sun) 08:51:29 1f5816 No.604163

File: 47f32ccdefcba82⋯.mp4 (2.91 MB, 642x720, 107:120, dance thread.mp4)

>>604041

As has already been pointed out by others in this thread, grooved slugs don't spin when fired through a smooth bore. The grooves are there to remove material so that the slug can swage easier in the choke while also keeping the full length of the slug fully supported as it is traveling through the barrel before hitting the choke.

What does sort of work and is very inexpensive is the rifled choke. Having a smooth bore for the majority of the length of the barrel followed by a few inches of rifling at the very end in a choke tube has been done and has been demonstrated to work somewhat well. You only need 2 to 4 inches of rifled bore to impart enough spin on a bullet to make it fly straight. The problem with this system is that it takes freebore to the extreme, can cause a second pressure spike closer to the muzzle, and the rifled choke can wear out more than conventional rifled barrels. You want the rifling to start at the throat of the barrel. After that first few inches it could go back to being smooth except it can't really because if it were tight enough to maintain a gas seal the friction would slow or stop the rotation, and if it were wide enough to permit free rotation all the gas would blow by and contribute nothing to the acceleration, and may even destabilize the bullet causing it to bounce side to side or change angle.

There really is no good way around rifling the bore except to change the shape the bullets so that they are aerodynamically stabilized instead of with gyroscopic stabilization.

That means hollow bases/skirts like on pneumatic pellet gun pellets. That could work in a modern rifle with a soft metal skirt around a harder, lighter metal core (think hardened steel core with a lead or copper skirt that peels away on impact) but there may be thorny legal issues with that sort of thing.

While the idea of rifled bullets is not going to work, it is good to see people considering novel approaches to ballistics and manufacturing. too much of the gun industry, especially the civilian side, is just stylizing these days.

Strelok 08/26/18 (Sun) 09:17:14 8cf10c No.604167

Would this electro-chemical machining that Finland and Hungary keep sperging over make more unorthodox rifling methods economically viable?

What sort of twist rate would you be looking at for a very long, thin, lightweight projectile based on that 'flywheel' principle of the 7.92x41 CETME and 5.56×38 FABRL?

Strelok 08/26/18 (Sun) 11:28:10 4aab74 No.604181

Smoothbore is the future of all small arms.

>Why does the atf hate smooth barrel firearms?

Because everyone knows shotgun slugs are copkillers which can go clean through a vest.

Strelok 08/26/18 (Sun) 19:37:58 1f5816 No.604269

>>604181

>Because everyone knows shotgun slugs are copkillers which can go clean through a vest.

But that's (mostly) wrong. Most slugs will not penetrate a IIIA vest, and only a few will go through any plate armor.

Strelok 08/26/18 (Sun) 20:08:34 7d2f84 No.604278

>>604269

Do cops wear plates nowadays? i thought they mostly wore kevlar/soft vests.

Strelok 08/26/18 (Sun) 20:16:31 4aab74 No.604280

>>604269

Sarcasm doesn't translate well, but that sentence was about what ATF believed.

Strelok 08/26/18 (Sun) 20:36:38 40aeb0 No.604284

>>604163

I'm bouncing around a squeeze-bore progressive rifling geometry that could be hammer forged. No sketches yet though.

Strelok 08/27/18 (Mon) 00:28:16 c9840d No.604337

Is polygonal rifling worth it or is it better to leave it more specialized roles?

Strelok 08/27/18 (Mon) 00:30:52 cb3d44 No.604339

>>604167

>more unorthodox rifling methods

Like what? Squeeze bore? Progressive rifling?

Most barrels nowadays are hammer forged anyway; you can make almost any arbitrary oddball rifling just by changing the shape of the mandrel.

Strelok 08/27/18 (Mon) 14:14:41 a37dad No.604497

File: 9be8e27b572e630⋯.webm (145.87 KB, 524x478, 262:239, traps.webm)

>>604339

not gain twist/progressive rifling

or squeeze bore with taper less than the depth of the rifling grooves

think about it, you gotta be able to pull the mandrel out after you're done