Not the Smooth Twist, Smooth Twist X, or ANY of the "newer" barrels but the ORIGINAL SMOOTH TWIST BARREL! Anyone know the Twist rates for .22, .25 & .30?
Original Smooth Twist Barrel twist rate?
- Thread starter Gerry52
- Start date
For the original Smooth Twist barrels consisting of a mostly smooth bore with rifling at the muzzle, pellets would skid through the rifling and pick up but a small amount of the twist rate. For example, the .22 was measured at something in the neighborhood of 1:150. Yes, one rotation in 150 inches. Many JSB pellets worked great with this slow twist but almost nothing else. Search for tests done by Harry Fuller for more information.
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WOW! Thanks. It's always amazing how accurate the OST barrels are for pellets considering the extremely short Twist @ the end! Have any idea of what Twist rate to enter on Strelok?
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An external ballistics app like Strelock or Chairgun is concerned with the twist rate of the projectile so you'll want to use the 1:150 value or at least something "big" by the usual standards. I did a little search and some guys were suggesting something like 1:60 in the larger calibers. As far as I know it's only used for calculating spin drift and let's just say good luck separating its infinitesimal effect on a pellet from wind effects and other sources of dispersion. I don't want to tell you to ignore it...but just ignore it 
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The twist rate in Strelok is to calculate stability factor which does not apply to pellets, more importantly calculate spin drift which does not apply to ST barrel so you can put 100 or 150 but ST barrels basically do not have any spin drift to speak of.
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Thanks guys!. @dc8cappie, I stressed in 1st post, NOT ANY of the barrels,liners but Original Smooth Twist. Different animal but thanks anyway.
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Gerry, I still think TO THIS DAY, the original .30 caliber Smooth Twist barrel is the best PELLET barrel ever made. I know you feel the same. Like is mentioned above, the pellets from the ST barrel resist Vertical Jump better than any that I have experienced. Yes, it may only be a difference of 1/4 inch, but that can be the difference between 1st and 10th places at 100Y BR... I like them so much I bought another used .30 Bobcat a year after I sold the one I won EBR with in 2019. Its ALWAYS zero'd, and NEVER has POI shifts, plus it seems the pellet just plain goes where you aim, EVERYTIME - no fliers!!!
I think ON AVERAGE, I can shoot higher scores with it than I can my .22 DS RW HP, but when the RW is spot on it can be just plain STUPID accurate and the RW can shoot the higher scores... I've never shot over 228 with my Bobcat, but have shot over 230 many times with my RW. I think though that if I took the average score over time, the Bobcat would come out on top.
I think ON AVERAGE, I can shoot higher scores with it than I can my .22 DS RW HP, but when the RW is spot on it can be just plain STUPID accurate and the RW can shoot the higher scores... I've never shot over 228 with my Bobcat, but have shot over 230 many times with my RW. I think though that if I took the average score over time, the Bobcat would come out on top.
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HOW on earth FX thought to design a barrel that has rifling in ONLY 7% of the barrel & get that kind of supreme accuracy is beyond me but we're glad they did! My affection & admiration of my guns just gets greater over time.
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The st barrel is the creation of Ben Taylor of Theoben Rapid . He also worked with Fx to develop the Royal and Boss action.
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qball..you are correct but sadly about the only one who has been able to work this out. Nobody it seems is also able to push a cleaning rod down the barrel and see how may inches it takes to rotate once.
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THe "Paradox" barrel has been around for over 100 years, as has the "Gain Twist" and almost anything else you can think of except for the Five R.
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I have an fx streamline in 22 and I have a 25 coming today. I will say the barrel is super accurate with pellets. My 22 works well with H&N barracuda 18. It will shoot crosmans well out to about 40 yards but they start to fall apart after that. The 25 streamline owner told me it shot well with hybrids but I’m not really a slug shooter but I may test that who knows. I know it is pretty silly to say especially after buying 2 streamlines but I firmly believe the original ST was a bit of a stumble. Lots of barrels shoot jsb really well, come on big deal. Why did fx rather quickly expand on that barrel? They knew the severe limitations created by the ammo pickiness those barrels pose. Who knows maybe the long range accuracy is noticeably better in the ST but out to say 65 I notice no difference. If you are like me and not really a slug shooter than the barrel is fine. Like I said it will shoot other pellets than jsb too. If I ever decide to go slugs I’m getting something that will push them harder than a streamline is capable of anyway.
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I recall reading years ago that the rate of twist starts slow then increases as it approaches the muzzle. Thus the rate of spin goes from zero to what ever it is at the muzzle but the spin is increasing with momentum even after the pellet leaves the bbl. so without some high dollar high speed photography it would be difficult to measure the effective rate of spin. Granted memory if a bit foggy on this but I recall it being a form of gain twist.
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