Gents,

If a 20 inch barrel, only had the last 6 inches rifled, what probems would I be looking at?

Roger QSL

Why do you ask, Grasshopper?
If you're experimenting, don't, the barrel makers have already done that for us.
If you have a worn barrel, I can't imagine how it got that way, but a jump of that far before hitting the rifling would have to deform the bullet quite a bit when it did hit, ruining accuracy. It might even cause a pressure spike at the wrong point and you might be looking for gun parts, maybe with a red and white cane.

Actually guns were made like that at one time. They were called "Paradox" .
The Idea was that you could shoot either a round ball, or use it as a shotgun.
Greener made these up for hunters in Africa.
To make such a bore you would have to rifle it then ream out the rifling as far as you wanted. Otherwise the rifling would not engrave the bullet.
Sounds like the ultimate in "frebore".
Good luck!

Gents,

I was curious along the lines of a pressure spike. The reaming sounds plausable.

Just how much rifling does it take to stabalize a slug? Especially, a heavy 458.

Roger QSL

Lets look at the difference between a bullet starting from zero revolutionary velocity hitting the leadin to the lands,and the same bullet going 2000 fps straight down a smoothe bore, and then hitting a restriction in the barrel in the form of a spiral set of lands that want to make it go from a forward vector to a spinning vector at 100,000 or 200,000 rpm ):

I fear the rifle would want to twist from your hands, or fly forward, or just generally resist the acceleration from a straight flight into a spinning flight. This would most likely just rip the jacket off the bullet, or separate it from the core. WIth lead bullets sometimes this is just a stripped bullet.

It would be rather bad news all around.

However, this is just based on my understanding of physics, as I have never tried it.

However, try a simple experiment: start running from standing, and then jump off a pickup truck going 10 mph and see how you make the transition.

anyway, have someone take pictures if you try it. They could be entertaining.

[ 10-08-2003, 05:25: Message edited by: Jameister ]

Sounds like a good way to reduce felt recoil - having the bullet pull the rifle forward when it hits the lands.

In all seriousness, you would have to cut a forcing cone at the beginning of the rifling. Much the same way as a forcing cone is cut into the barrel of a revolver, and for the same reasons.

Sort of apples and oranges, but I have fooled with a 20 ga. shooting slugs through a smooth bore, rifled choke tube, and a rifled barrel. Accuracy through the tube, shooting sabot slugs, was much better than shooting through a smooth bore, but not near as good as shooting through a fully rifled barrel. There was no twisting, or anything else out of the normal when you shot. I also tested Brenekie full bore slugs through the smooth bore, rifled tube, and rifled barrel, giving roughly the same results. By going from a rifled choke tube to a fully rifled bore, I was able to gain another 25 yards of usefull accuracy. While the tube would hold 3" at 50 yards, then shooting patterns after that, the fully rifled bore would hold 3 inch groups out to 75 yards, and "only" opened up to 11 inch groups by 100. Too big to hunt with, but with the rifled tube, after 50 yards the slugs started tumbling and more often than not missed the target completely at 75 yards.

Gents,

Well some interesting posts. Didn't quite solve my questions though. Hoping to hear from someone with technical knowledge of barrel rifling.

The response with the long leade aiding with recoil reduction, appeals, but not sure of the science.HI

The old paradox rifling was something that interested me. Slow start with increasing rotation. Seems this should aid in reducing pressure spikes.

Has anyone tested this system. Especially with big heavy slugs?

Thanks for your inputs but still not enlightened as to the original questions.

Roger QSL

This is just an idea, not advise; but if you were to decide to experiment with this, you may want to start out shooting a fully rifled barrel and add freebore in small increments. If you shoot through a chrony, I would suspect that you would see an increase in velocity with the useful addition of freebore and then a decrease when it begins to lose its utility. This if just off the top of my head. from what I keep hearing about freebore, accuracy will likely errode somewhat through the whole experiment.

If I were to offer advise, I would say to start with very small increments.

Paradox rifle/shotguns were fairly accurate out to 75 yds,as they used bullets weighing up to
900 gr in some 10 gauges. The last 3 inches of barrel was rifled.ED.

I had similar experience to Big Bore. I have a 12 gauge smooth bore barrel into which I can put a rifled choke tube. I don't see any difference in recoil or accuracy (using Remington Slugger non-saboted rifled slugs), and I don't feel any twist when I shoot.

H. C.