Why is the Smooth Twist barrel only accurate with JSB ?

Hello everyone. I'm new here, and I found this thread, because I was looking for some info regarding my FX T1 in 22, and its problems.
Now, to the ST barrel and JSB accuracy, here is my experience.I shoot it with different pellets, Gamo magnums (16gr), JSB (26gr), Gamo long range (22gr), Crosmans (14+gr)...and results are really interesting..
The best group of those were with Gamo magnums (16gr)...about 2-3mm (cca 1/10in) at 10m ..and by far the worst with RWS 10gr wadcutters (2 cm and even more - say around an inch).
At the time I'm waiting for JSB heavy's , since they are about the same weight as Gamo magnums, only of much higher quality. I'll tell more, when I get them
JSB monsters (26gr) gave me a bit bigger group than 16gr gamos, but not much, (another mm or two...well that is 50% more:) )I belive (and, If I'm wrong - well who cares), "problem" lies in timing. In ST barrel, the pellet hits rifling at the end of barrel (last two inches). Pellet is moving there at the top of its speed, so if ther isn't much material that rifling could grab to - and wadcutters have enough material only at allready soft skirts - they are just skimmed..
On the other hand, if the barrel is fully rifled, pellet gets grabbed by rifling from speed 0 to full speed, so the "meat" of pellet is less important that used in ST.
Also, if you have really heavy pellets, regardless if they are "fully bodied", they have a lot more of inertia because of its weight, so they also need more time in rifled part of barrel to give them full rotation...and those two inches at their speed , litteraly don't cut it :). Besides, heavy pellets usually need higher twist rate, to get properly stabelized... so I guess in case of ST barrels, there is a compromise of speed of pellet and actual rotation that they get becasue od their mass, ws. the material (that lands it self of their mass) that they provide to rifling...
I belive, only real advantage of ST is manufacturing cost.. I think it is cheaper to make precision ST barrel then full rifled precison barrel. Now, how that precision at ST is marketed onwards..that is different thing
So that advantage is only for manufacturer.

MOD EDIT: This post triggered a different off topic discussion. It has, therefore, been moved here -http://airgunnation.dev/topic/having-some-trouble-with-my-22-fx-t12/?view=all#post-31267 
 
I use JSB Exact Kings .25 25.4gr in the Bobcat w/ smooth twist and groups are hole in hole at 25 yards. Had a tin of benjamin domes .25 laying around and printed a group with .25 smooth twist and I got hole in hole also at 25 yards. 

If anyone wanted to send me different pellets to put through the bobcat .25 i would be happy to do it and give a report. :)
 
I think most of the fx haters on here prob never shot or seen a fx st barrel gun! They proven themselfs time and time agin in competions world wide ,i personaly have met the owner and his son , and watched them take on world class shooters with no money spared guns locked into benchrest rails they competed with production guns with only a bipod!!! At 75 yards with the fx boss .30 cal st barrel i think he got 14bullseyes winner got 16 i think with a rail gun mind you this was a very windy day! Not a easy thing to do all guns have certin pellets that shoot better in them all of my guns prefer jsb but will shoot others good
 
DKL - it seems like there are an awful lot of negative posts from you towards FX & their Smooth Twist barrels. The original poster did not ask for opinions on FX or the Smooth Twist barrel, he asked WHY the smooth twist barrels seem to be most accurate with JSB pellets. Try to keep your responses relevant.

Thank you
👍.. true, plus FX liner to sleeves has a lots of fixture point, if assembled taking all the measures correctly (most people don't ever mention line of sight straightness to the jam nuts also after all proper assembly) FX also as good as any barrel (bdw I won't mention any barrels been better)
 
On other thread many people said that JSB pellets do not work well on .22 Cal Daystate Red Wolf.

As a matter of fact my Red Woof .22 Cal shoots the better with H&N Baracudas 21.14 grain pellets. Same story with my Wolverine .22 HP. Same story also with my .177 Cal Revere regulated.

So..... If you want a rifle that shoots accurately with all pellets and slugs, buy an Airgun Technology, those are accurate every time on every shot.