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.
Then how to form the "twist" lands without deformation of the achieved interface perfection? Difficult perhaps. More so if multiple twisted end sections are to be considered fitting to a single smooth section.
There will always be a transition in a two piece barrel even if only a perception, this may cause commotion to some.
I don't say it is impossible to achieve useful results, but the process will be expensive, and perhaps best suited to development programs that determine optimum dimensions to be applied to production methods.
I am sure the price point on the manufacturing level is less than $100 per.
James you may find my post up top of interest.
Though long, it still does not cover all that I have done with the Elite since getting it 3 months ago. The short story is that in the past few weeks Fredrik and I have now become acquainted and he has been preparing to experiment with the implications of my results and of suggestions I have made. ... Best regards, Harry.
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.
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.
The factory nominal barrel twist rate equivalent is 1:16 inches.
April 6 2012, 1:00 AM
If you read my report up the page you will see the flight spin rate for two particular barrels.
But don't presume that those rates are absolute as I know that pellet momentum at point of contact with the rifling can change the flight spin rate.
Momentum is velocity and mass dependent so either of those can alter effective spin rate. Nor is it that simple as I also have evidence suggesting that pellet-to-barrel wipe area/ bearing surface can confound predictions when comparing a diabolo with a bullet.. I can get flight spin rates from 1:44 to 1: 64 to 1:90 inches from pellets and bullets from the one barrel, the variables being velocity, pellet mass, and pellet bearing surface area. ... Kind regards, Harry.
Just a quick assessment on how much skidding is going on
April 6 2012, 12:30 PM
A run through the numbers suggests that the difference between the rifle twist rate and the realized pell rotation (or lag of) would be greater than one complete "land to land" pitch over the twisted section.
This condition would result in "Maximum deformation" of the pellet shape due to interaction with the twisting elements. That is, the entire periphery of the pell would experience deformation due to contact with the twisted portion.
Yup! There might be some shearing,bending and friction heating going on, and that may be unique to ST configuration.
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