Smooth Twist Barrels

From what I've read, 1:16 for a LW barrel and about ten times slower for a smooth twist.

ST barrel a lot slower less damage when you hunt because less spin when it goes through prey.
When you cut with knife your self you do not feel it but if you drill your self you will feel it in a second..
Get LW a lot cheaper less pellet fussy and it is not speed fussy.
I do not buy FX Any more because of those dam ass barrels

In answer yes, we did the research starting back 5 years ago:
Some reading for you. It began when I initiated the question and Dan Brown took up the challenge ( I didn't have an ST barrel just then):

June 19, 2010.
http://www.network54.com/Forum/79537/message/1276988390/

I subsequently carried out the similar experiment with my .25 ST Elite and the same rifle with an ST .22 cal barrel. A synopsis of the results:
Quote: Dec 27 2012: in answer to a similar question to yours:
"But first to answer your question. Yes. I established 1:70" to 1:80" effective spin rate for .25 Kings from my FX Elite's nominal 1:16" ST "rifling"..
Same rifle with spare ST .22 cal barrel was 1:64" with JSB. When Fredrik tested at my prompting he got 1:44" in his rifle's .22 cal.
However my research showed effective spin rates depend upon the pellet ( wt etc ) and the muzzle velocity (or rather probably the velocity at contact with the beginning of the ST "rifling"). The ST barrels have gone through many iterations before, and since Dan's initial tests.
Since Fredrik conceded the stripping phenomenon to me early this year, he determined to experiment further following our discussions. It would be costly but he indicated resolve. He has yet to send me the hardware result, but was resolved to make some new barrels with 1:30 and 1:40" twist instead of 1:16" for he and I to test. ... I look forward to testing those when he manages the logistics. " ... end quote

I don't know if Fredrik got around to further experimenting. But I do know that at that time end Dec 2012, he was on his 18th iteration of developed ST barrels. My .22 barrel was one of the 16th iteration! Fredrik never stops experimenting.

Some mention and figures here, and some analysis in a practical sense, relating to the "skidding" of pellets through the couple of inches of the ST rifling section of the barrels.
http://www.network54.com/Forum/79537/message/1333679371/

You may like to compare the above data on ST barrels with this done with conventional rifling some tome before.:
http://www.network54.com/Forum/79537/thread/1281248469

Hope you get some of the picture from this .... Kind regards, Harry/ Yrrah.

I wouldn't put any stock into the wound difference between the two. Even with powder burners twist rate has been shown to have very little effect on wounds.. 

"FVA"I wouldn't put any stock into the wound difference between the two. Even with powder burners twist rate has been shown to have very little effect on wounds..

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I agree. I'm sure if you asked a squirrel if they felt the difference between the pellets going through their brain or heart the answer would be no. Even back when BBs and pumpers were being used, the end result was the same, a chunk of metal going through vitals killed the prey.

While I must admit I have cut myself with a knife by accident I just never have drilled myself. So I will give recognition to the person that has and the pain involved. But since a smooth twist barrel is generally thought of giving about 1/5 the spin rate on the pellet compared to a LW barrel. For a wound 2 inches deep would the pain be much different if the drill bit was going 1000 rpm versus 200 rpm?

I’ll let this be confirmed by someone else!

"17bullet"While I must admit I have cut myself with a knife by accident I just never have drilled myself. So I will give recognition to the person that has and the pain involved. But since a smooth twist barrel is generally thought of giving about 1/5 the spin rate on the pellet compared to a LW barrel. For a wound 2 inches deep would the pain be much different if the drill bit was going 1000 rpm versus 200 rpm?

I’ll let this be confirmed by someone else!


You have to add in the fact that a pellet isn't fluted like a screw or drill and regardless of twist rate likely making less than half a turn during the penetration phase.

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Why does everyone want to beat down on fx ? If its not the smooth twist barrel they are blaming fx of fixing the extreme benchrest shoot in their favor its bs. The smooth twist has proven itself time and time agin! It has won most of the extreme benchrest shoots!!! I have shot the extreme it is not easy i watched fredrick shoot beside full benchrest guns locked into rest 's etc with a new prototype .30 boss with no bags vice etc just a bipod!! I think he got third just dont see where all the hate comes from but think its just jealousy tell you the truth just my two cents! 

"DKL"ST barrel a lot slower less damage when you hunt because less spin when it goes through prey.
When you cut with knife your self you do not feel it but if you drill your self you will feel it in a second..
Get LW a lot cheaper less pellet fussy and it is not speed fussy.
I do not buy FX Any more because of those dam ass barrels

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I think a better analogy would be an slow rotating ice pick or a fast rotating ice pick (the 'tool' must be radially symmetrical and can not change for the analogy to be accurate).. In which case I fail to see how one would be more or less destructive than the other.

But, analogies aside, my experience shooting from both brands of barrels also contradicts your claims. Fantastic claims require fantastic evidence. 

My experience with Fx (bobcat .25) are very good. I've got the AA ultimate sporter, the Steyr hunting 5, Daystate air ranger - all well done guns and to a lot higher expence than the bobcat - but when I go out to have a good time in the field or the range, it' s the bobcat I'm choosing. Can't help it. The cat is dead accurate, and gives me a hughe amount of shots.
Turboken 77, I'm very happy with your response, thumbs up for that!
Bye the way - my Wildcat .22 has been announced ready for shipping from sweeden. Now I'm looking for a light, compact, high magnificationed scoope - don' t we all.........

Thanks Yrrah I wondered how St compared in twist rate compared to rifled barrels .The rifling serves only one purpose and that is to stabilize the projectile in flight to improve accuracy .Too little twist and You have yaw which means the bullet is not accurate at any range .Too much twist and the projectile looses accuracy at longer ranges but will be stable at closer ranges .Barrel length,projectile shape,weight,and speed play a part .This is observed in some of the break barrels shooting 1250 fps being deadly accurate up to 30 yds or so and then total useless at longer ranges .but by using a heaver pellet accuracy increases because speed decreases .The killing power of a projectile is determined by the weight and speed of the projectile at impact (ft lbs of energy).Then projectile at impact starts to deform and quickly starts to tumble creating the womb channel .The spin has nothing at all to do with the knock down power of a projectile other than putting it where You aim.Lead hardness and projectile design do play a role in the knock down power .This information was provided for the few that might not understand bullet ballistics and help Them make wise decisions in there gun purchases based on facts not old wives tales or individuals prejudices .Stan

Blackdiesel I am not sure I totally agree with you on the brain shot and heart shot, the brain does not feel pain and is the favored shot by the SAS for a reason, it is a very quick kill, if not instantaneous, a heart shot might not kill immediately and might cause pain. I doubt whether squirrels could really give us an answer on it though, either way they would end up dead. Neil.

The amount of spin required is related to the amount of stabilisation the projectile requires to stay on the correct path on it's journey to the target. Pellets are quite short and stubby so don't need so much stabilisation as say a high BC bullet. If you look at the profile of a high BC bullet, it's much the same as the profile of an aircraft wing. The only problem is that a bullet flies in the opposite direction, it's like trying to fly a plane with the wings stuck on the wrong way around. So a high BC bullet needs a lot of stabilisation. A pellet in profile looks nothing like a wing and need far less stabilising, so relative to a high BC bullet does not need a lot of stabilisation. For those of you of a more technical nature, it's all to do with the difference between the centre of pressure and the centre of gravity. In an arrow and an aircraft wing, the centre of pressure (on an arrow provided by the fletchings) is behind the centre of gravity, in a bullet the centre of pressure is in front of the centre of gravity. Imagine what would happen if you tried to fire an arrow backwards, that's what bullets are doing. The only thing that stops the bullet from tumbling over is the spin that induces gyroscopic forces in the bullet that are so strong that the bullet doesn't flip around until it reaches it's destination or slows down to transonic speed.

What happens to the prey when the projectile arrives is related to factors such as penetration and the dumping of energy into the prey. Contry to what many gangster movies may suggest, a bullet does not actually drill its way into prey like a twist drill cutting through metal, it stabs or punches its way in.

Below is a video that demonstrates what happens when pellets (.177 in this case, but would expect things to just scale up for larger pellets) are fired into clay.





Of course the tumbling effect of a bullet does cause a lot of terminal damage, but something akin to a ball bearing as indeed a pellet is, doesn't cause the bulk of it's damage by tumbling.

"NeilClague"Blackdiesel I am not sure I totally agree with you on the brain shot and heart shot, the brain does not feel pain and is the favored shot by the SAS for a reason, it is a very quick kill, if not instantaneous, a heart shot might not kill immediately and might cause pain. I doubt whether squirrels could really give us an answer on it though, either way they would end up dead. Neil.

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Well the squirrel's answer would still be the same in that he didn't feel a difference between one pellet or the other going through his brain no matter how fast it was rotating.

My response was as to the difference between brain shot and a heart shot and any pain felt. I think a brain shot would involve no pain no matter what was used, a heart shot could cause pain, no matter what the animal is or what shot or twist rate is involved. Personally I don't care what twist rate a barrel has, if the gun is dead nuts on accurate who cares what twist it has? I have an FX air gun, I have no idea if it has the smooth twist barrel or not, all I can tell you is it is one of the most accurate guns I have ever owned, so in my books it is a great gun. It seems like with air guns there are good barrels and some not so good, even on the same make and model, I guess I got lucky and have one of the really good ones. Neil.. 

"CAAirgunner""Hi guys. I was wondering if Smooth Twist barrels spin the pellets faster than LW barrels. Also, does anyone know the Smooth Twist's rate of twist? Has anyone ever compared a Smooth Twist to a CZ barrel?"

CA Airgunner, did you catch the answer to your first two questions you actually asked from the references I posted? I have more data but thought that would be enough reading for one session. I'm sorry I don't have a CZ barrel but the video below may help.

In response to some of the other comments: at 900 fps MV, the spin rate from my ST .22 cal barrel is approximately 165 revs per second or 10,000 rpm. That is plenty of spin to support the "arrow stability" of a shuttlecock shaped diabolo pellet .
If that statistic isn't convincing then perhaps watch the slow motion flight of these .25 cal Kings capturing pellet stability all the way to a 51 yard swinger. The "group" would be less than 1/4" ctc: FX Elite Smooth Twist barrel, JSB Kings; some left to right wind:
http://vidmg.photobucket.com/albums/v392/Kyogle/FX%20ST%20Elite%203%20JSB%20Kings%2051%20yds%20pig%20silhouette%20Jan%202012_zpskh9z9wld.mp4

You can draw some conclusions as to the "accuracy" of this FX ST barrel and pellet stabilizing ability ........ Best regards to all, Harry.

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Just a video that talks a bit about FX barrels and the goings on at the FX factory (includes interview with Fredrik himself and the inventor of the smooth twist barrel Ben Taylor).

 

My FX FT has made a smooth twist believer out of me. I was skeptical at first but two tins later it has dispelled all of my accuracy doubts. 

Jamie