FX Smooth Twist barrels on other guns?

[zandrew]

What is the benefit of the smooth twist barrel? Does the smooth twist cut down on friction and increase muzzle velocity?

I am just wandering what is the gains over traditional barrel designs?

[rkr]

What is the benefit of the smooth twist barrel? Does the smooth twist cut down on friction and increase muzzle velocity?

I am just wandering what is the gains over traditional barrel designs?

They are much cheaper to manufacture. A small increase in speed of the pellet. I shot against .30 bobcat on our last 100m br and I was stunned how poorly it shot when compared to my .25 BSA.

[zandrew]

What is the benefit of the smooth twist barrel? Does the smooth twist cut down on friction and increase muzzle velocity?

I am just wandering what is the gains over traditional barrel designs?

They are much cheaper to manufacture. A small increase in speed of the pellet. I shot against .30 bobcat on our last 100m br and I was stunned how poorly it shot when compared to my .25 BSA.

I have thought about lapping the barrel and then using a dry film lubricant like what is used in engines on piston skirt and bearing faces and see how it does. They are designed to greatly reduce friction. I would think if they can hold up inside engines designed for torture races like le mans that it should hold up for a barrel where lead is used. I could buy a cheap crosman barrel and see what happens.

The issues is how to apply evenly and also how would the barrel hold up when heating it since you have to heat it too 300° Fahrenheit.

[PigButtons]

I have thought about lapping the barrel and then using a dry film lubricant like what is used in engines on piston skirt and bearing faces and see how it does. They are designed to greatly reduce friction. I would think if they can hold up inside engines designed for torture races like le mans that it should hold up for a barrel where lead is used. I could buy a cheap crosman barrel and see what happens.

The issues is how to apply evenly and also how would the barrel hold up when heating it since you have to heat it too 300° Fahrenheit.

I don't think that the temp will have any negative effect on a steel barrel. I do NOT see how you will get the film to be uniform in the barrel as I would think that there has to be some gravity related migration of the material as it transitions from a dry "film" to a cured product during the heating process. Also, though I may be wrong ( I often am ), the film is used in areas where oil would normally be present between the two metal surfaces of dissimilar materials and therefore different friction coefficients being presented to the oil film which results in shear thereby causing friction at higher levels than normal engine components. The piston skirts and the bearing inserts are softer materials than the cylinder sleeves and the crankshaft bearing surfaces which they face against and will tend to gall up under this stress. This combined with the extreme temperature and linear speed of the moving parts make the use of the dry film lubricants beneficial. The air gun barrel and the pellet don't have the same kind of oil film drag properties to deal with, nor the temperature, nor the constant high speed movement for hours at a time. Lead is quite slick as it is in the environment of traveling through the barrel at high pressure and high speed.

Along these lines however I have experimented with Renaissance Wax on a few pellets after cleaning the barrel of various air guns. It works well on barrels that have a tight bore relative to the pellet. It didn't work on the Smooth Twist barrel; after about 5 pellets the accuracy went bad very fast and never improved until the barrel was cleaned again. Since I was getting such good results from just cleaning the barrel often I didn't pursue it any further.