Original Smooth Twist Barrel (and it's not from FX)

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Saltlake58

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Apr 9, 2015
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Utah, United States
OK, so I watch Smarter Every Day from time to time. The old man is a "Metrologist". These people measure things. Somehow that lead into a helical gun barrel from the Civil War. Point being, it was fundamentally a octagonal smooth twist barrel. Dude with the Whitworth canon is drilling bullseyes at 600 yards. Slow motion muzzle blasts are cool too!

https://www.youtube.com/watch?v=T-xMCFOwllE

Look at the Whitworth Rifle and bullet. The canon is incredibly accurate considering the technology. 600 yards!

I guess this means what's old is new again.

and, I'm not sure if this is the original smooth twist, but it's sure close.
 
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Smarter Every Day is a great channel, and because he does so much Physics work, and ballistics employs lots of physics, he does quite a bit, plus he's from Georgia, so very familiar with guns. Good combination.

Gotta wonder what other historical tidbits are out there. I know there was an Oval version of the Smooth Twist as well, but it didn't work so well.
 
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I am not sure what "smooth twist" is, but there are a few different forms of rifling....I don't think I would count the withworth as a smooth twist. It is a mechanical fit, the bullet fits into the cuts into the rifle.

I have not watched your video but do know a little about Whitworth, aside from coming up with one of the first machine standards for fasteners (whitworth threads) anyone with an old british car will know this, he came up with this rifle as well, it did work just not real well, black powder was really the downfall of his rifle, just fowling was too much.

Polygonal rifling would be closer to what I would call a "smooth twist" as there is really no rifling cut into the barrel as we usually think of it, it is nothing new as well, I know glock has used it, as well as the CZ82-83 IIRC. 

Then micro grove, the Marlin system, while not really smooth like the poly it does have a different take on the groves and I guess the most easy to say it is it grabs the bullet in a different way as to not "cut" into it as much.

If I was to call anything smooth it would be poly, they really are smooth to your eye, they are easy to clean....micro groove can be a real pain if it gets leaded up, and if you want to put time in grab a marlin that is micro grooved that is not shooting well....chances are the gun needs a real good cleaning.


 
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Cherokee140 - I think you are really close on all of this. The Whitworth rifle is also in the video. One Civil War Collector had a Whitworth bullet in perfect (oxidized, but otherwise perfect) condition, probably dropped by a soldier. They said the rifle was very accurate, but you may be correct that the Black Powder fouling of the day was the downfall for any round that required a clean barrel to shoot well.

If I remember my history correctly, the Minie Ball was developed for rifles that fouled. Because the skirt expanded to fit the barrel, it could be used in fouled guns, though accuracy suffered the longer the gun went without cleaning.

Agan, if I remember correctly, the FX Smooth Twist is a "Pentagram" shape, no grooves, just a twisted 5 sided barrel hammer forged over a mandrel. When the round pellet enters the barrel, the pellet reshapes into a pentagram to fit the barrel because it's soft lead. It seems to be a very similar principle between the two, FX Smooth Twist and the Whitworth, except the Whitworth ammunition is manufactured to match the barrel dimensions.

Do watch the video, it's interesting and really fancy slow motion of the muzzle blast of the canon.
 
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Not much new in airguns , the only thing I've seen since the late '80s is the huben valving set up. It is excelent to know history for just that reason, lot's of OLD ideas to try and re-incorporate into our more modern sthuff.

Like the 2 post above this one, some good nearly lost info in there. I'm thinking I've heard the same regarding hollow skirts in the old days.

"Smooth twist" ( at least as in fx ) to me is not "hammer forged" but rather pressed - terms may have changed faster than I have tho-.

A Vid for cherokee and others that might like to know ( and I just saw it on the internet and am not savy, could be Abraham Lincoln spoofed the vid, nah )

https://www.youtube.com/watch?v=gFcaDYICq8g



John


 
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Do a quick google on polygonal rifling, now I don't own an FX but I am betting this is going to be what they use.



And really the rifle whitworth made was a failure, it was expensive, did not take standard ammo, and fowling really hindered it after a few shots. I want to say there is a black powder channel out of the Czech Republic that has a repro rifle.

The thing that whitworth gave us that really made the biggest impact is the fasteners....with out this mass production does not exist, everything was different, each screw nut and bolt was hand made and made different, this screw would not fit in a hole that was not made specifically for it....think about that for a sec, your video touched on it for a sec, but this is really huge. This was the start of the industrial age....for good or bad, this is what gave us our world today.
 
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I actually knew that the smooth twist barrel has been around for a very long time and that it was nothing new when FX started using it.
Click to expand...

Except that the rifling is pressed on from the outside, who else was doing that? You must have a source as you knew it wasn't FX.

Original smooth twist is

Smooth bore till the last 2 inches or so with yes polygon rifling thats pressed on from the outside causing a choked barrel. If anyone has a source of Fredrik borrowing this idea from anyone please cite it. If you don't know what you're talking about maybe you should not try to imply that this idea is stolen.
 
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Click to expand...

Original smooth twist is

Smooth bore till the last 2 inches or so with yes polygon rifling thats pressed on from the outside causing a choked barrel. If anyone has a source of Fredrik borrowing this idea from anyone please cite it. If you don't know what you're talking about maybe you should not try to imply that this idea is stolen.
Click to expand...

Glem has it right. Others are guessing. But I think I see the "red herring".

The FX ST 5 lands rifling is pressed in from the outside of the barrel as grooves which then raise rhe lands in the last couple of inches on the inside of a smooth bore blank. The result is a land contour somewhat resembling polygonal but isn't. In the later STX barrels the rifling is full barrel length.

There is no resemblance to Whitworth.

However when the pellet strikes that last couple of inches of the original ST rifling, the pellets strip through and emerge with a much lower spin rate than the actual rifling. In my original study JSB pelllets spun at 1:64 " from the 1:16" twist rifling. (Note that different weight pellets result in different spin rates from the same barrel because of differences in impact momentum when they strip through the rifling).

Now therein possibly lies the source of the errors in thinking that ST is a rehash of the old Whitworth.

Because the pellets have stripped through the ST rifling they do not emerge with defined grooves and lands but basically with just 5 flats. My original pics of pellets, caught in teased out Merino sheep wool, showed this perfectly. Thus the pellet does appear somewhat like a Whitworth bullet.

This pellet profile was not intended and when I made Fredrik aware of these dynamics he was most surprised and spent a weekend duplicating my study model and results. Ultimately the result has been the STX revision with full length rifling, and with the possibility of accurately producing liners which can induce any spin rate desired to optimise individual pellet accuracy. ... My FX STX Crown is super accurate with all three versions of the FX King .25 cal pellets. It has a 1:28" twist rate . ... and the rabbits in the vicinity of our farm are most displeased as they have lost over 400 of their mob to it during 2018. 

I hope 2019 will be kind to you all.

My best regards, Harry Downunder, where it is presently a pleasant 84 degrees F.


 
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And just for general knowledge in case some people hadn't seen it up close.

Original Smooth Twist "naked", threaded cap goes over this. (rifling pressed from outside)

1545970365_2695959165c25a2bd4f9e26.82457902_20181227_200510.jpg


Smooth Twist X liner (rifling pressed from outside but entire barrel length)

1545970441_3730043275c25a309adcbd0.39656295_20181227_201024.jpg



 
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The original discussion was not about how the rifling was created (pressed from outside vs more traditional rifling techniques), but about the similarities of the Whitworth rifling and accuracy of the gun with the FX rifling and accuracy of the gun, nothing more.

The term Smooth Twist X is also a bit of a misnomer. The original marketing was that the barrel was a smooth bore until the pellet hit the last few inches that contained the "Twist". Now, the Smooth Twist doesn't really have any smooth bore, but is not rifled end to end. The newer STX barrels do resemble the full length rifling of the Whitworth, and while pellets start round, they end up with the 5 flats you referred to, much like the Whitworth bullet or canon shells with 6 flats.

While we may disagree on the nuances of the barrels, the point is that the rifling FX uses was really invented long ago. This takes nothing away from FX as designing the machining to create the original Smooth Twist barrels, and proving the incredible accuracy was an incredible undertaking, and did show the Airgun world that there's more to rifling than the traditional styles we are used to. 
 
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