Fast rifling

[Story]

Ok, theoretical question:

What would happen if I used a looong barrel rifled at 1:20?

 

[Tahquamenon]

Your projectile will rotate more before exiting the muzzle when fired within the given 1:20" barrel length than one within a slower rifled barrel.

How long of a barrel in which caliber?

Potentially greater range and accuracy.

 

[Story]

Umm.... four foot long. And about 20mm bore. ::

 

[Doc Arroyo]

I guess you would have to shoot a round ball really slow to keep from stripping the rifling....Or you could build a really long conical and shoot it really fast. (Ain't that what the Vulcan does?)

 

[Zonie]

Ok, theoretical question:

What would happen if I used a looong barrel rifled at 1:20?

I'm not sure I understand the question.
What would happen to what? Are we talking about slugs or patched round balls?

In general, the length of the barrel doesn't have much to do with anything except velocity if we're speaking of black powder guns.
With black powder, you can get increased velocity by increasing the barrel length, but for a given charge, there comes a point where adding more length won't increase velocity enough to be worth the extra weight and awkwardness.

As for patched round balls in a fast twist barrel, the important thing seems to be the depth of the rifleing.
Shallow rifleing grooves don't work very well with round balls.
If they are deep enough to prevent stripping or slipping of the patch, IMO, the fast twist just imparts unnecessary spin to the ball. It doesn't take much to stabilize a round ball and it's dam hard to know if it keyholed or not! ::

 

[CrackStock]

Sounds like someone got hold of a military surplus barrel.

CS

 

[Story]

Keyhole?

Yeah, you understood the question. Actually, I found out the 20mm Vulcan barrel has gain twist rifling. It'll be interesting to see how deep the rifling is.
Thanks.

 

[Doc Arroyo]

I thought so. A builder in this neck of the woods reamed the Vulcan barrel smooth, breeched it and built a very nice wall gun out of it.

Good luck on your project!

 

[LSU TIGER]

I bet it works great for keeping cats outta the garbage, Doc! :crackup: :youcrazy:

 

[Zonie]

:imo: There are several things to think about for your barrel.

First, a 20mm bore is somewhere around .794 diameter. It might be hard to find a .784 dia pure lead ball to shoot in it.

The barrel was used (I assume) and is probably worn so the .794 might be less than the actual bore size. This would mean you might need a .795 ball or so, but you won't know until you've measured what you have.

Because it's rifled, it will make a very poor shotgun unless you want to use it for killing things close up.

Paying someone to ream the rifleing out and make a smooth bore might be an idea, but it will be somewhere around a 8 guage.
Finding wads might be a problem. If you did find some, the kick will get your attention. You might think of a wall gun like the one shown in another post:

 

[Story]

Thanks Zonie.
I'm comptemplating a really big Jaeger rifle... like this:
http://www.collectorsfirearms.com/al1300.htm
Check the depth of the rifling in the last photo.
Didn't that fellow in England make molds to custom order?

 

[BLAHMAN]

That's a pretty fast rate of spin, and I'd bet that it would be good for bullets as opposed to a round ball!

 

[fho]

I think that it is a bullet gun. According to my fiqurers the bullet would be 4.108 inches long. This gun looks like it is mounted on some kind of a swivel. With the Lowe's formula the bullet length would be 4.063 inches long. I don't how much the bullet would weight but it would be heavy. :imo:
Olie