Could I make my own "smooth twist" barrel..?

If shooting high velocity, I think you might want to make a ST-X barrel, where you are going to polish the rifling the whole way.

I think one of the limitations of the ST barrel was that if a pellet was pushed too fast, when it engaged the rifling at the end of the barrel, it would strip lead from the pellet.

The ST-X liner can handle velocity upwards of 1,000fps without stripping lead because the rifling grabs the pellet immediately. This is just going by what I've read in these forums. Ernest Rowe might have given this information.

CHUCK would have some input on this.

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Mmm. I did consider just polishing the whole length of of grooves (landings) to reduce the friction and possibly the spin. My understanding is that the "standard" twist rates of our air gun barrels that mimic those of fire arms are not conducive because a powder propelled projectile is moving so much faster, at such a higher pressure and thus needing a (relatively) high twist rate. Where as compared to a air gun, shooting say 900fps, could never be anywhere needing a similar twist rate as say a 22-250 shooting 3600fps...! also when the center of pressure of a diabolo pellet is behind the center of gravity, in contrast to a bullet which is the opposite, the pellet doesn't need any spin stabilization to keep from tumbling, just a slight spin to counter gyroscopic inconsistencies in the pellet's construction. 

I beilieve I saw an Ernest Rowe video were he polishes the landing grooves of barrels with 200 strokes of fine grit sand paper in 3 different grits.. this would essentiallly be doing what you're talking about I think right? Maybe you're on to a better idea Bob...

In powder burners the heavy bullets require more spin not less. Having read this unless I am misunderstanding it sounds like you are thinking the opposite for the slugs??? I do understand more twist means more friction which might affect an all lead bullet . Interesting subject obviously it has to be just right for a given projectile.

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If we're speaking in relative terms and a powder burner is shooting a 40gr bullet at 2000fps and has an optimal twist rate of 1:16, that would mean I would have an optimal twist rate of about 1:64 right? But I bet my barrel twist rate is somewhere between 1:8 to 1:16 - I really have no idea but I just feel like it's got to be way too fast regardless of what my 2500psi can produce compared to the tens of thousands of psi a powder burner is shooting at. I have more research to do for sure, just wanted to punt this question out there because I assume there is no way a lot of you haven't considered similar

I've heard that the regular smooth twist barrels don't seem to like the redesigned monsters. I've seen it on 4-5 different threads on different shooters with the Original smooth twist the the redesigned monsters don't do well at all. But I heard the smooth twist X does much better.

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Yeah, I think I jumped the gun - I was actually aware of that - the ST is basically just designed for one pellet and the STX is more pellet friendly from what I understand. I think Bob's suggestion to head towards the STX idea is better idea. I'm going to watch ER's video on polishing down the landings again.