Roller Muzzle Design Help

[popgun pete]

Yes, it is Oreste Vacondio. We discussed his work in the Rollergun Group many years ago and well before this article was published in 2003, so it was good to see him again. I think many here would benefit by a close reading of this article, and any others that he may have written, as he must have extensive experience with rollerguns and is a true expert. The rollergun that he shows here is very compact and a masterpiece of design in my opinion. VIrtually no larger than a standard eurogun, there is an economy in its design which is very appealing to the technically minded and it should make for a good lateral tracking weapon with very little increase in drag.

[doyenofcastle]

how much the overhang should be ?if shooting low may be shorter will better ?

[gspearguns]

Originally Posted by doyenofcastle

how much the overhang should be ?if shooting low may be shorter will better ?

I usually use 7 inches (18 cm), max 20 cm.

[popgun pete]

Check out the rollergun shown on post #51 here which has been made in the Ukraine. http://www.garpun.de/forum/index.php?topic=622.45

Some of the photos show the roller muzzle up close and you can see the flanking wishbone lifters and catchers; and the gun's bright orange colored rollers!

[deanmc]

Originally Posted by Behslayer

What would be great is if anyone has some high res, slow motion, zoomed in video of different roller muzzles firing. then you can really get an understanding of what happens.

Not a wood roller but 2 identical builds I just competed. Both suffer from the same problem, the spear travels in an arced trajectory, shoots low. I'm going to try some of the suggestions here to see if I can get these to shoot straighter; File down the shark fin tabs, file down the muzzle so the track on it sits 1mm lower than the track on the barrel and ease off on the pre-tension a little. I might add some lead to the muzzle as well, you can see it jumps a bit.

The guns are 43" long. The bands are 5/8"X 20" long. 9/32" shaft. MVD Roller Pro G2 head

The video is only four shots but each one is repeated once or twice in slow-mo, I also zoomed the best I could. The longer shots are 20 feet away from the target, shorter shots around 16 feet

https://youtu.be/2pfc8CUi9B0

[gspearguns]

I made several classic rollerguns and never had a problem of shaft end rising...

[popgun pete]

Originally Posted by gspearguns

I made several classic rollerguns and never had a problem of shaft end rising...

Very nice! The cost of these weapons (ballpark figure only)?

[gspearguns]

Originally Posted by popgun pete

Very nice! The cost of these weapons (ballpark figure only)?

Monorollers between 950 and 1100 USD, but these are all smaller models 80-95 cm. Double 1300-1600.

[popgun pete]

I can see you have the clearance grooves along the stock for the bands as discussed earlier on this thread. I like your carbon fiber roller axle side shields and integral muzzle front bar that carries your line rigging hooks, excellent attention to detail and a high standard of finish. Open muzzle combined wishbone lifter and catcher at the front is a nice bit of design work and creates a good impression of logical development.

[Wood Guy]

Originally Posted by Behslayer

Good insight. Bill the threaded Standoffs, do you make those or can you buy them somewhere to size?

What would be great is if anyone has some high res, slow motion, zoomed in video of different roller muzzles firing. then you can really get an understanding of what happens.

Here's where I get mine. I use the 1/4" diam. but they are available in several diam. They come in 1/2" increments, but I can cut some down if you need an odd length.

https://www.mcmaster.com/#threaded-standoffs/=15347ph

[memosub]

Originally Posted by popgun pete

I recall a foreign guy made a rollergun for commercial sale which suddenly disappeared (patent problems maybe). It was a eurogun type with a very compact rollergun muzzle and some round objects in the hollow core of the bands that looked like a snake had swallowed some prey animal, or two snakes as there was a bump on either side. These bumps in the bands would not go through the nip between the band roller and some smaller secondary roller sitting in front of the axle that was a form of band catcher. Those bumps halted the wishbones because they were a few inches in front of the wishbone and they hit the band catcher first. I think the guy's name started with a “V”, Vacondio, or something like that.

http://www.apneamagazine.com/il-roller-gun-716

Oreste Vacondio

[Behslayer]

Thanks Bill!

Pete, that Roller is very cool and original.

G, those are nice. The Doppia is my favorite the way you combined the wood with composite.

[popgun pete]

Originally Posted by Behslayer

Thanks Bill!

Pete, that Roller is very cool and original.

G, those are nice. The Doppia is my favorite the way you combined the wood with composite.

I thought so too, hence I have now added the photos of that Ukrainian rollergun to my post.
Note the stylized "fish profile" roller axle side shields and the tiny rocket fins on the line slide!

[Behslayer]

Dean, If you can get a El Cheapo Tripod and put in Pool on highest res videoing the muzzle from the side on a few shots I bet we can figure out what is happening. (Shoot both sides if possible)

[deanmc]

Originally Posted by Behslayer

Dean, If you can get a El Cheapo Tripod and put in Pool on highest res videoing the muzzle from the side on a few shots I bet we can figure out what is happening. (Shoot both sides if possible)

I'll see what I can rig up. Hopefully I can get back in the pool next week.