Velocity vs Bore Drag for a Typical PCP

[CarsonRatSniper]

K.O. - The progressive gain twist barrel is an interesting idea and one Mike Sayers could certainly make a mandrel for.
It only takes money LOL 

[rsterne]

Mike, I think you will find that Mike's mandrels are short and moved along the barrel as it is hammered.... I have no idea how you could remove a full length, variable twist mandrel, once the rifling is formed.... unless I completely misunderstand the process.... I would think a variable (gain) twist barrel would require button/broach rifling with a very short button/broach running in a variable rate guide....

Bob

[CarsonRatSniper]

That's right...I remember now Doug was saying his mandrel was only 8" long or something - Never mind!

[K.O.]

I actually think a short tapered bore/lands barrel could conceivably be  done but I honestly do not know...

The gain rifled barrel if produced with button rifling will have lands that narrow which I see as a positive... The draw back is that it has limits on how radicly you can vary the twist rate...

I know cut rifling has it detractors and with PB PRESSURES and heat maybe deservedly... (Unequal stress)

but the ability to totally customize rate (zero  to 1 in 96 or 1 in 18 or 1 in 8 at any progression) and the lower demands of air rifles on the barrel seem to make it a option worth looking at...

http://www.bartleinbarrels.com/Trifling.htm

I think that the barrel is the one thing that has lagged in the modern air rifle as a part of the system and just as Pope developed his system

there is room to come up with a system for a propellant that is at its highest psi at the very beginning and practically demands as low drag as possible at that moment for best performance...

So I asked myself  what would Pope  do because he came up with a  system...

http://riflemansjournal.blogspot.com/2010/08/history-pope-rifle-barrels.html.

[Tomg]

So what you are saying is the FX approach "smooth twist" is on track of what you are talking about. It's not progressive but by the time the pellet is halfway down the barrel, there is no spin torque applied, so it's sort progressive.

T

[K.O.]

So what you are saying is the FX approach "smooth twist" is on track of what you are talking about. It's not progressive but by the time the pellet is halfway down the barrel, there is no spin torque applied, so it's sort progressive.

T

the way they are doing it the pellet is not seeing a gradual increase it smacks into it... can you say velocity and pellet picky... IMO...