I was thinking about the smooth twist barrel. It has a very short,

I was thinking about the smooth twist barrel. It has a very short,

Joined: August 22nd, 2001, 3:27 pm

April 5th, 2012, 8:33 pm #1

section of rifling, I'm wondering if a device could be made that had adjustable pitch rifling and fit on the end of a smooth bore barrel?
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Joined: August 22nd, 2001, 3:27 pm

April 5th, 2012, 8:42 pm #2

inserts, in different pitches.
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Joined: June 7th, 2010, 12:14 am

April 5th, 2012, 9:08 pm #3

And so would always be a point of distrust when "accuracy" is the subject.
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Joined: April 23rd, 2009, 9:20 pm

April 5th, 2012, 9:09 pm #4

inserts, in different pitches.
WOW! This could be a really revolutionary feature on airguns! Almost indecent! To choose the "choke/pitch" for the pellet, and not the pellet for the gun... It's the end of the pellet fussy slavery!!

Hmmm. I'll be thinking about it all the weekend. And is not a new thing! Almost all shotguns uses interchangeable chokes for a long time!

Great idea! Mr. Perotti!
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Joined: August 22nd, 2001, 3:27 pm

April 5th, 2012, 9:50 pm #5

And so would always be a point of distrust when "accuracy" is the subject.
I don't see alinement being an accuracy issue, but scope settings would need to be changed.
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Joined: September 15th, 2000, 3:23 pm

April 5th, 2012, 10:00 pm #6

section of rifling, I'm wondering if a device could be made that had adjustable pitch rifling and fit on the end of a smooth bore barrel?
there is no rifling in a Smooth Twist in the conventional sense. The grooves imparted on the outside of the bore acts more to change the shape of the bore than to create any sort of a groove. The shape change (which is gradual) is what imparts a spin on the pellet as it passes through the transition and then out the end. An interesting side is that as the pellet passes through the ST portion, it does leave visible lines where the lead is no longer making contact with the bore walls that look very much like rifling grooves. What looks like grooves are in reality the points of a pentagon vs. the smooth walls of a round tube.

To explain further, different pellets, specifically by length and weight, require a different spin rate to maintain stability. It is my understanding that the numbers have been run for the Smooth Twist that would allow the barrels to be made for just about any brand of ammo. They chose the JSB because they work closley together on development, and the consistancy of the JSB manufacturing process is pretty well known. I was told that if I NEEDD a barrel that just HAD to work with one particular brand of ammo, I should ask to see if it were possible.

Put these two things together, and I would think it possible that interchangble tips could be made. Do I think it will happen any time in the near furure? No.

Regards,
DaveG
See more picts @http://davegcustomstocks.com
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Joined: April 4th, 2005, 6:09 pm

April 5th, 2012, 11:13 pm #7

The hard part about making a barrel is drilling a straight hole; rifling is easy by comparison.

Why not take a crap, cheap barrel and bore it from .177 to .20 or .22 and then thread the end and add a rifled/choked end?

Jim
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Joined: June 7th, 2010, 12:14 am

April 5th, 2012, 11:15 pm #8

I don't see alinement being an accuracy issue, but scope settings would need to be changed.
But In my mind I picture a thread on extension that adds the twist section to a smooth bore, much like the interchangeable chokes in the shot gunning world. and I envision the extension about 15-20 cm in length.

That construction would necessarily add a parting line where the two elements join. An annular interface. I know the junction could be made as to be "nearly nothing", but that nearly would spawn conversation.

Did you have an alternate configuration in mind?
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Joined: June 7th, 2010, 12:14 am

April 5th, 2012, 11:18 pm #9

The hard part about making a barrel is drilling a straight hole; rifling is easy by comparison.

Why not take a crap, cheap barrel and bore it from .177 to .20 or .22 and then thread the end and add a rifled/choked end?

Jim
the fun would start when the pell hit the rifle. Yarrah would be grinning ear to ear
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Joined: January 2nd, 2010, 6:09 am

April 5th, 2012, 11:45 pm #10

there is no rifling in a Smooth Twist in the conventional sense. The grooves imparted on the outside of the bore acts more to change the shape of the bore than to create any sort of a groove. The shape change (which is gradual) is what imparts a spin on the pellet as it passes through the transition and then out the end. An interesting side is that as the pellet passes through the ST portion, it does leave visible lines where the lead is no longer making contact with the bore walls that look very much like rifling grooves. What looks like grooves are in reality the points of a pentagon vs. the smooth walls of a round tube.

To explain further, different pellets, specifically by length and weight, require a different spin rate to maintain stability. It is my understanding that the numbers have been run for the Smooth Twist that would allow the barrels to be made for just about any brand of ammo. They chose the JSB because they work closley together on development, and the consistancy of the JSB manufacturing process is pretty well known. I was told that if I NEEDD a barrel that just HAD to work with one particular brand of ammo, I should ask to see if it were possible.

Put these two things together, and I would think it possible that interchangble tips could be made. Do I think it will happen any time in the near furure? No.

Regards,
DaveG
See more picts @http://davegcustomstocks.com
Many high end paintball barrel kits have one base and a bunch (3,5 or more) of tips of different diameters that thread onto the one common base. This allows the shooter to match what ever paintball diameter he is using, improving accuracy.

I think a smooth barrel of about 16" permanently mounted to the receiver with a few different 3"-4" long rifled/pentagn/hexagon bore shaped tips of different twist rates would be pretty cool. That "should" allow a person to change tips to match whatever pellet he's shooting.

Doug
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