SpudFiles

anyone have any ideas on how to rifle a 2in PVC barrell, i havent seen any 1 3/4 dowels latley

Instead of using a dowel, why not try using another piece of pipe?

thats what i was thinking but pipe being hollow would probably not hold a nail in place to well =/

Then fill it with something, maybe epoxy, where the nails need to be secured.

hmm thats what i was thinkin, alright looks like its off to the h depot to secure a large quantity of epoxy

lol i dnt think youll need that much

I think I'm going to try this on my 1" barrel. I'm making the rifling tool out of a 7/8" dowel and some 1" wood screws. If I come up with anything good then I'll be sure to post it. The method seems to work fine on PVC though from the little bit of messing around I've done so far.

Update: I just tried using this method on a piece of 1" PVC pipe around 36" long. However, instead of trying to pull the dowel through the barrel, my friend slowly tapped it through with a hammer while I twisted the pipe with my hands. It seemed to work pretty well and we got a pretty even spiral. We just finished testing some projectiles made from short sections of 1" wooden dowel wrapped in tape with a screw through the center as a weight. The results were good and the projectiles were flying, as far as I could tell, very straight. However, I want to do some more experimenting since I was only using the gun at around 20psi as to not scare the neighbors. I could definitely see where the grooves cut into the projectile which was pretty cool.

Managed to rifle a ~1m section of 1/2 in SCH 40 using this technique. However, when I pushed my ammo down the barrel (I used a 1/4" Carriage bolt inside a nerf dart with the head cut off and partially wrapped in duct tape) it didn't seem to be spun by the rifling. What type of ammo are people using with rifled barrels, and can anyone confirm that the grooves produced this way actually do rotate the projectile?

Hmm, I think ice/pykrete would probably grip the grooves well since it's a good seal in the barrel.
To see if the projectile spins, you might want to try this premature idea of mine:
Take a sponge, and shape it into a small rod that can be tightly shoved into the barrel. Weight one end of it so when shot out of a barrel, it will fly straight. Now soak the sponge, and fire it out of a rifled and unrifled barrel. If it works, the centrifugal force from the rifled barrel's spinning will pull water out of the sponge as it leaves the barrel in a large ring or something. The regular barrel will have no spinning force, so the water should just stay with the sponge or fall off it as it flies.

What do you think?

noob of noobs wrote:Hmm, I think ice/pykrete would probably grip the grooves well since it's a good seal in the barrel.
To see if the projectile spins, you might want to try this premature idea of mine:
Take a sponge, and shape it into a small rod that can be tightly shoved into the barrel. Weight one end of it so when shot out of a barrel, it will fly straight. Now soak the sponge, and fire it out of a rifled and unrifled barrel. If it works, the centrifugal force from the rifled barrel's spinning will pull water out of the sponge as it leaves the barrel in a large ring or something. The regular barrel will have no spinning force, so the water should just stay with the sponge or fall off it as it flies.

What do you think?

interesting idea!
hmm, I could only see it working on tight fitting sealing ammo
like sponges...or spuds:D

I love how this gets kicked up every now and then

I'm working on my newest rifling tool for copper,15mm copper.It's going to use a die method of making the grooves and lands.If all goes to plan it will make them with large groves and small lands so more of an effect on the projectile.

I have an idea, or rather i hope you guys do
I have noticed after about the 100 shots that have been through my hybrid with Aluminium .50cal barrel that it has started to form it's own rifling, what could be the cause of this?
The twist is approx 1.5 turns over a meter and there are several of them with differing depths (the deepest would only be ~.25mm)

My theory rests on the the combusted gases turning in a circular motion parallel with the chamber, (how this would "grip" the slug is beond me) it is ignited from the rear as uses either stainless slugs or cast projectiles, any ideas?

I may be able to design a self rifling projectile

That's really weird, and cool, but I don't think that we can combust pressurized gases in our PVC barrels to rifle them. Besides, although the nail + dowel method is more work and less cool, it produces grooves just fine, the problem I'm having is that I can't get the grooves to spin the projectile. What kind of ammo are you using in the hybrid? Does it have spiral edges or anything?

I just tested out this method with a 54" rifled barrel and surprisingly had some convincing success. I made a projectile out of a snuggly fitting 1" wooden dowel with a screw and nut in the top. I then fired it from 50ft at about 30psi (I was in a backyard and wanted to keep it quiet) at a piece of scrap metal. I was able to get consistently straight shots which all impacted on the head of the screw (I could easily spot the "+" shaped indents made in the metal). When I shot the projectile straight up at low pressure I could see the projectile rotating with only a slight wobble. I can't wait to see what happens at higher pressures.

niglch wrote:I just tested out this method with a 54" rifled barrel and surprisingly had some convincing success. I made a projectile out of a snuggly fitting 1" wooden dowel with a screw and nut in the top. I then fired it from 50ft at about 30psi (I was in a backyard and wanted to keep it quiet) at a piece of scrap metal. I was able to get consistently straight shots which all impacted on the head of the screw (I could easily spot the "+" shaped indents made in the metal). When I shot the projectile straight up at low pressure I could see the projectile rotating with only a slight wobble. I can't wait to see what happens at higher pressures.

Are you sure the round isn't aerodynamically stable? Where is the front to back (FTB) balance point? If the FTB is more than an inch or so in front of the center of the dowel then the round may well be aerodynamically stable (and rifling isn't needed).

Steel has a density that is what about 10X most woods? So the screw and nut may well have shifted the balance point far enough forward to make it stable in flight. Easy enough to determine if the round is aerodynamically stable. Find the front to back balance point and tie a string around the round there. Spin the round on the string over your head. If the round tumbles it is unstable, if it doesn't it is stable. (You may have to get it spinning pretty fast.)

Another, less accurate method is to simply compare the location of the measured FTB balance point with the FTB balance point of a piece of cardboard with the same outline as the side view of the shell. If the center of mass is more than one gauge (the diameter of the round) ahead of the center of mass of the cardboard then the round may be stable. If the center of mass is more than 2 gauges ahead of the center of mass of the cardboard then the round is almost certainly stable in flight.