Like I said, I assumed the same thing but after slugging the bores, both rifles slugged out at .220
22lr barrel twist for Long range
- Thread starter joehunt
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Like I said, I assumed the same thing but after slugging the bores, both rifles slugged out at .220
CIP groove diameter for .22LR is 5.58mm (.219"). The bores seem to have diameters that correspond to CIP specs. SAAMI groove diameter is larger at 5.64mm (.222"). Of course bore size is not always consistent between makes of rifles, perhaps even occasionally between individual rifles of the same brand.
Further reading about .220 Long Rifle indicates that it is the same as .22 Long Rifle. The marking was once used in Britain and was replaced by the more familiar one.
Have you ever slugged the bore on an old Martini????
The triple question marks suggest indignation, but it's not clear why as there's no argument or disagreement. Whether anyone else has slugged a Martini bore doesn't change anything. You've said the Martini bore slugs at .220" and there's nothing unusual with that. As noted above, it's the same as what a bore made to CIP specs would slug. If you or anyone else slugged a bore made to SAAMI specs the results would be different at very near to .222".
Yes. There are several issues.
A quality bullet tolerates ovre-sptabalization.
A poor bullet gets even worse if it is spun too fast.
And then there is the gyro effect. A bullet is stable, like a gyro. The curve it follows down range gets to be fairly steep at longer range. But the bullet, because it is a gyro, stays pointed exactly the way it was pointed when it left the barrel, so at long range is is coming down, with the point aimed up a bit. If the spin rate is not too fast, the bullet will tip over to follow the trajectory.
However, if you recall gyros, if the gyro is moved, it will tip 90 degrees to the movement. So if the bullet tips over to follow the trajectory, it will also tip sideways.
A quality bullet tolerates ovre-sptabalization.
A poor bullet gets even worse if it is spun too fast.
And then there is the gyro effect. A bullet is stable, like a gyro. The curve it follows down range gets to be fairly steep at longer range. But the bullet, because it is a gyro, stays pointed exactly the way it was pointed when it left the barrel, so at long range is is coming down, with the point aimed up a bit. If the spin rate is not too fast, the bullet will tip over to follow the trajectory.
However, if you recall gyros, if the gyro is moved, it will tip 90 degrees to the movement. So if the bullet tips over to follow the trajectory, it will also tip sideways.
Twist rate for the 22 LR has been 1-16" most commonly. Some rimfires, designated 22 Short or long only have slower twists [1-18"]
Suhl 150 Standard match rifles have varying twists, depending on original purpose. Some were 1-16", but they were as slow as 1-19"
When the Remington 504 was released, most of the LR barrels were 1-14.5" [who knows why] Slow twist barrels can mess up the
accuracy in colder weather. Fast twists are generally deemed unnecessary for overall applications. It will be of interest to see if a
1-9" twist will have any real benefits at any range. Dave.
Suhl 150 Standard match rifles have varying twists, depending on original purpose. Some were 1-16", but they were as slow as 1-19"
When the Remington 504 was released, most of the LR barrels were 1-14.5" [who knows why] Slow twist barrels can mess up the
accuracy in colder weather. Fast twists are generally deemed unnecessary for overall applications. It will be of interest to see if a
1-9" twist will have any real benefits at any range. Dave.
Now you're being presumptuous. It was intended as a serious question.
In all honesty, I didn't check CIP specs and didn't realize they were different. That's one of the reasons I like this site. I get to learn new things regularly and on several occasions have been wrong about things.
As for the British designation of .220, it seems plausible to me that the stamp was intended to designate their mean diameter.
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