Reply To: FX reveals the "Crown" and the Smooth Twist "X" barrel system!

Forums PCP Airguns FX reveals the "Crown" and the Smooth Twist "X" barrel system! Reply To: FX reveals the "Crown" and the Smooth Twist "X" barrel system!

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zebra
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“Yrrah”

“zebra”

 


Does that mean the new barrels are rifled over the whole length instead of just the last inch like the regular ST barrels? 

If it does mean that, I’d love to hear from FX what the thinking is behind the change. I know the LW polygon barrels are the latest fashion in certain circles but it would be great to see if FX’s testing found a meaningful advantage over traditional rifling and their ST design.  

 

Zebra,
Yes the rifling is full length of barrel.

Some explanation:  Because of differences in weight and velocity and therefore momentum, different pellets skid through original ST “rifling” to leave the barrel at different spin rates. None conform to the actual barrel rifling which is 1:16″. In the original research done by Dan Brown and myself, we measured spin rates between 1:64 and 1:160 with different wt pellets and calibres.
When Fredrik himself then repeated our tests he observed 1:44 approx. All from 1:16 barrels.
Now the new STX barrel liners with full length ST rifling will result in all pellets leaving the barrel at the barrel’s twist rate regardless of pellet dimensions,  as is the case with ordinary barrels. 
OK so what is the advantage gained?  We should be able to select a liner that optimizes pellet spin rate for best accuracy for that pellet and possibly those of somewhat similar weight, length and design.  Think what is the case with your centre fire rifles which long ago optimized twist rates from 1:14 to 1:7 depending on bullet dimensions, profile and wt.   Other air rifle makers are not producing barrels with a selection of twist rates and if they did, you would be up for the cost of each complete new barrel.

FX has optimized the normal .22 ST barrel for best accuracy with 18.1 gr Heavy JSB Exacts. They shoot other quality pellets very well too, 15.9 gr JSB, Baracuda H&N,  Eunjin etc. But optimized for the JSB Heavies.  Now when I get an FX Crown I will be able to optimize for my favourites  including Polymags, and Piledrivers with their  extraordinary long range ballistic coefficient.
This is exciting as I may have only a few years of shooting left – turned 80 yr a week ago! …
I hope this makes some sense.  … Best regards, Harry.
 


It makes sense to me. 

I can think of one additional potential benefit that would be at least as important (if not more) for me. If you happened to get unlucky by receiving one of the less accurate barrels (all guns come in a range of accuracy), it would be easier to switch it out for a more accurate one. It  reduces the risk on an expensive purchase a little. 

Obviously you can pay to get a new barrel blank machined for any gun but it’s such a PITA as well as being expensive and time consuming for air guns. 

I am intrigued by the potential to tailor twist rates for the pellet although it’s just marketing speak until we see it in practice. 

I haven’t see any test results showing that the best twist rate for a JSB 25gr is x while an H&N Barracuda needs a twist rate of Y to be optimal. That sort of testing seems beyond the resources of most of us. Even if I had two barrels with different twist rates, I wouldn’t know if the more accurate one was due to the tr or it was just a better barrel sample. I would need help to be able to benefit from this feature.