Does barrel riffling cause the slide to torque in the fame and cause the slide to rub the frame differently from left to right?
I also read that a hard fit barrel helps eliminate barrel torque in the frame thus helping to increase accuracy. I strived to eliminate this torque when I fit my Kart barrel.
Here are some examples of my 45 frames that all show that the left side of the frame has more polish marks than the right side of the frame. My first 1911, a Colt Commander, is at Colt now getting some work done but has these same polish patterns. I first noticed the difference between the right an left polish marks on the Commander but thought it was because how the Colt was built. Now that all of my 45 show this trend I suspect barrel rifling.
Left side with consistent and more polish marks than the right side.
Right side with less polish marks
Coincidence or barrel rifling?
All I can say is get yourself a cork for a bullet and glue it to the end of a stick with a indicator line on it. Poke the cork through the chamber, into the rifling, put the greased muzzle onto something smooth, put a case over the end of the dowel and push on the case.
Q: Does the barrel have a left-hand twist?
Q: If so, which way will (did) the bullet/cork/dowel rotate?
Q: Which way did the barrel rotate when viewed from the chamber end?
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Q: Does the barrel have a left-hand twist?
They are all mil-spec so I believe it is counter-clockwise (left-hand) looking from the chamber to the muzzle or clockwise looking from the muzzle to the chamber... just as your pre-Kahr AO.
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Q: If so, which way will (did) the bullet/cork/dowel rotate?
Haven't tested... but it should rotate opposite of the rifling.
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Q: Which way did the barrel rotate when viewed from the chamber end?
Soon... but the polish marks lead me to believe that clockwise from the?
Wait a minute... I thought that I had this figured out... all of a sudden my world flipped backwards...
I think I need to think about this more...
Y'all can look in the barrel, either end, and see the direction of twist. LH is spec. and "normal".
The barrel will try to twist RH.
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They are all mil-spec so I believe it is counter-clockwise (left-hand)
looking from the chamber to the muzzle or clockwise looking from the muzzle to
the chamber... just as your pre-Kahr AO.
Don't let the difference of looking into the chamber or muzzle end mess you up. When looking in the muzzle end the bullet would be coming toward you and rotating (as you view it) CW. But when viewed from the chamber end it's going CCW.
The handedness of the rifling doesn't change, so when looking in the muzzle I just pretend the bullet's going away from me to figure out how the rifling rotates it - and whether it's a left-hand or right-hand twist.
Of course in the Southern Hemisphere where the Coriolis force is opposite what it is up here in the Northern Hemisphere...
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Coriolis force is opposite what it is up here in the Northern
Hemisphere...
You had to add in Coriolis acceleration... the fact that the north pole dosn't really move rather just spin but whereas the equator is book-in in comparison... and every point in-between has a different speed...
Why did I ever choose "ball" ammo?
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Wait a minute... I thought that I had this figured out... all of a
sudden my world flipped backwards...
I think I need to think about this more...
Be careful. From what little I've read by Stephen Hawking, that's what happens when you cross over the event horizon (the point of no return when falling toward a black hole)!
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Why did I ever choose "ball" ammo?
I'd guess it is because you don't have a Whitworth with the hexagonal bore using hexagonal bullets.
Fortunately, JMB did not follow Whitworth practices when he designed the 1911 or we might be shooting 'hex' ammo.
Haven't had much time to fully digest Single Six's insightful idea in Post #13 of this thread:
http://forum.m1911.org/showthread.php?t=90183
But maybe something like the following is responsible for what you observe in your guns. The bullet being forced to twist down barrel doesn't cause it. What causes it is when the slide hits the impact abutment in the frame and the frame is twisted CW by the thumb of a right handed shooter - the path of least resistance. The frame going CW under the slide is essentially the same as the slide going CCW atop the frame.
You right-handed?
As I understand the dynamics of a 1911... the barrel does "wind-up" as a round is fired and does causes the barrel to twist against the slide and then it does cause the barrel knees to twists against the slide stop and react against the frame. Which in turn will to wear the frame rail just at I illustrated in the pictures posted above...
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You right-handed?
OK... now that makes sense too... the pistol always pulls away from the weakest part of your grip....
Where is JMB when you need him?
Slide shouldn't torque. The barrel is affixed to frame by the slide stop so the load is there too. Slide may not match the frame perfectly so the deferences in the wear
The barrel isn't fixed to the frame of a 1911. Small caliber pistols use fixed barrels. The 45 doesn't.
The barrel's link hole has diametrical clearance (oversized) to the slide stop pin thus allowing the barrel to tilt while the bullet torques down the barrel rifling. This tilt reacts against the slide. The slide also has clearance to the frame. This slide to frame clearance allows the slide to be pulled against one side the the frame and pushed away from the opposite side of the frame.
This is clearly what all the pictures that I posted above show. That the slide is pulled from left to right.
Depending upon the fit of the barrel, most of the torque is absorbed by the frame. I like to have a very close tolerance between the lug channel in the frame and the barrel lower lugs. Mainly, it aids in supporting the contact area of the slide stop pin and the lower lug foot print, which is very small to begin with,, and not a stable platform. It needs all the help it can get. It also reduces the forces transmitted to the upper lugs. The better the slide to frame fit, the less uneven wear occur. There are many variables that contribute to the over all stability and alignment of the barrel. Twist direction matters not... Most of the barrels I install are a right hand twist. You are witnessing the importance of precision fit and alignment of "every" aspect of the 1911...
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You are witnessing the importance of precision fit and alignment
of "every" aspect of the 1911...
I will attempt to hold tighter clearances for a more precise fit on my next build. The next one won't be a general purpose 1911 but rather a "attempt to build a target pistol" effort... yikes...
The good news is that I just bought a forged 4140 frame machined by Remsport from GB... now I will start looking for a slide.
Much of this bullet rotation/twist/torque was discussed about half way through this lengthy thread:
http://forum.m1911.org/showthread.p...e+energy+budget
It also includes RobL's calculated value (in Post #91) for the torque in the gun caused by the rotating bullet. He termed it "miniscule".