Right vs left barrel twist?

J

joneb

New member
Why are most barrels right twist?
I am not sure if spin drift and the coriolis effect are worth the worry, but in the northern hemisphere if the coriolis effect is said to cause the bullet to impact right of the target do to the counterclockwise rotation of the earth. And spin drift for a right hand twist can cause the bullet to drift to the
right, if this is true I would think a left twist barrel would be better in the northern hemisphere.
I realize the wind is the real culprit but my question is directed at long range shooting at 1000 yds and more.
 
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Shouldn't make a difference for coriolis, from my understanding of it.
Gunwerks i think did a video on coriolis. Mostly shooting long distance (1000 yards) east, then west. Had to do more with elevation.
 
Why are most barrels right twist?
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Had this discussion during a recent shooter's course at Camp Butner. Our consensus determination, which the instructor agreed with, was that the first rifled barrels were given a right hand twist for whatever reason... maybe tool limitations or maybe no other consideration other than a decision had to be made and it was chosen to twist to the right. And most everyone else copied the first guy, and almost everyone has been doing it ever since. Humans tend to be creatures of habit, and unless there is a need to change something then we seldom do.

Another example of this is the fact that railroad gauges are nearly identical to horse-drawn carriage axles, and even chariot axles dating back to Roman times. Could the railroad gauge have been changed and possibly have been more efficient? Sure... but a lot of factors played into it, and some of the first locomotives actually pulled carriages originally built as horse drawn carriages, but with modified wheels. Engineers noticed that it worked, and no one ever decided to change it. Same lies true with barrel twist.
 
Since probably 99% of all rifle shots (my guesstimate) are at less than 300 yards, we're back to Hillary's famous question. :)

FWIW, from my college daze of over a half-century ago, the coriolis force acts in an east-west direction. Its primary effect would thus be highest on a north or south shot. None on a shot directly to the east or west.
 
Why are most barrels right twist?
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Actually, the reason is simple. They are made that way so that with every shot, the barrel torques itself tighter. The bullet hits the rifling, and inertia tries to keep it from spinning, but the rifling forces it to spin. Equal and opposite reaction causes torque on the barrel in a clockwise direction, tightening the barrel. Once someone figured that part out, tradition takes over.

But what of the barrels with left hand twist, you ask? Colt made left hand twist barrels as well, and there are no stories about the time Colt SAA barrels unscrewed themselves, so I think the effect is grossly overstated.
 
Sound like another gun urban legend.

I believe there were something like 3 million Model of 1917s made (add in the P14s and ......)

Ain't none of them come unscrewed.

The story is that the brits thought that the right drift was really cool for Australia so they made them for shooting down under. US didn't change of for the 1917.
 
" Equal and opposite reaction causes torque on the barrel in a clockwise direction, tightening the barrel."

If that was a concern just reverse the barrel and receiver threads.
 
TD's and 03's sight?

How come the long range portion of 03's and TD Buffington 1884 sights were at a noticeable angle? Don't know about Krag's as all I have seen recently have been "sporterized and redid" by Bubba. Didn't Lee-Enfields and 1917's have a left hand twist? Modified right hand twist?

Also, where do these twenty year old threads come from in this day? :confused:
 
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I used to have a Colt revolver with left-hand rifling that was made in 1902. It had been fired a lot and the barrel never came unscrewed. I still have an old Ford truck that has left-hand threads on the wheel lug-nuts on the left side of the vehicle. Apparently, some truths are only true in theory, but in practical application, have no discernable effect whatsoever.
 
Isn't it because most rifles are sold in the northern hemisphere? If they were sold in the southern hemisphere they would have the opposite twist, kind of like the phenomonon of why toilets flush clockwise vs. counterclockwise depending on which hemisphere they are in?? ;) Yes, I'm just kidding!!!
 
"...Why are most barrels right twist?..." Because that's how the rifling machine, most of which are modified engine lathes, was made. Makes no difference one way or the other.
The only thing that happens is the muzzle jump goes in the other direction if the twist is left.
 
How come the long range portion of 03's and TD Buffington 1884 sights were at a noticeable angle?
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Because the spin drift after things out at 2500 yard! (exaggeration but....) (which no one shot in those days) - but of course they had to complicate the sight just in case.

The stupid thing is that 5 mph wind across the bullet path (effective regardless of angle, more angle more velocity of wind needed of course) would counter the drift adjust.

All nonsense but that's the military for you.


Didn't Lee-Enfields and 1917's have a left hand twist? Modified right hand twist?
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Yes the Brits used left hand twist as I noted above.

Not sure what you mean by modified right hand twist?

All OEM 1917 barrels were left. US produced WWII replacement were right. they still shot the same oddly enough.
 
Also, where do these twenty year old threads come from in this day?
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Not sure I understand this one. The OP is dated June 19, 2018, and checking my computer it says today is 6/21/2018, so 2 days not 20 years.
 
The majority of all people are right-handed. More threaded screws are installed than are removed. A right-hand screw is easier on the wrist when installing.

So, there might have been some similar thought in the early days of rifling with the equipment of those olden days.

Dangfino...
 
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