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True understanding of calibre?


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Old 07-11-2013, 01:43 AM   #11
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I'm on my second beer and I'm still confused. But glad I'm not the only one is confused by caliber. Thanks for all the explanations. I'm just going to order the sizes I need and leave it at that.


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Old 07-11-2013, 01:49 AM   #12
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Quote:
Originally Posted by nitestalker View Post
A pound of powder is 7,000 grains if you load 100 grs per cartridge you be able to load 70 rounds from one pound.
I'm assuming you left out a zero here. Should be 700 bullets, not 70.

By the way, what load uses 100 grains of powder, anyways? Most of my rifle rounds are around 50 grains. Pistol rounds even less.


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Old 07-11-2013, 03:29 AM   #13
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Quote:
what load uses 100 grains of powder, anyways?
Common in muzzle loaders. Or if you shoot a 50-110.
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Old 07-11-2013, 04:00 AM   #14
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Quote:
Originally Posted by gandog56 View Post
I'm assuming you left out a zero here. Should be 700 bullets, not 70.

By the way, what load uses 100 grains of powder, anyways? Most of my rifle rounds are around 50 grains. Pistol rounds even less.
No, he is right 7000/100=70.
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Old 07-11-2013, 05:13 AM   #15
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Quote:
Originally Posted by KJG67 View Post
I'm on my second beer and I'm still confused. But glad I'm not the only one is confused by caliber. Thanks for all the explanations. I'm just going to order the sizes I need and leave it at that.
I'll drink to that!
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Old 07-11-2013, 05:33 AM   #16
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Here is the simple answer. Caliber=Diameter.

The word is used widely for a variety of things. When I am grafting fruit trees using the whip and tongue method I must be very careful to match the caliber of the scion wood to the branch that is accepting the graft or the graft will have a lower chance of success.
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Old 07-11-2013, 01:16 PM   #17
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Quote:
Originally Posted by c3shooter View Post
Here is a cross section of a rifled barrel. Europeans measure like THIS-

Attachment 109709. What they CALL a 7.62mm actually is about .312, so it fills the low spots.

WE measure low spot to low spot- so what WE call 7.62 mm is about .308 inches across. See why this stuff is a PITA?

I believe you have this backwards. Calibre is measured from groove-to-groove, not the land-to-land as you have drawn.

The lands put rifling marks/grooves in the bullet and cause it to rotate. If the land to land measurement were the same as the bullet measurement then the bullet would not rotate and it would be like shooting out of a smooth bore.

You can check this if you have a Lyman manual. Lyman always lists the "Groove Diameter" of all test barrels and firearms used. For example Lyman 48 page 216, 308 Win, Groove dia .308 inches.

EDIT:
Never mind, you are correct, I didn't read the "European" connotation at the beginning. By Bad!

Last edited by mseric; 07-11-2013 at 02:54 PM.
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Old 07-11-2013, 03:06 PM   #18
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Quote:
Originally Posted by mseric View Post
I believe you have this backwards. Calibre is measured from groove-to-groove, not the land-to-land as you have drawn.

The lands put rifling marks/grooves in the bullet and cause it to rotate. If the land to land measurement were the same as the bullet measurement then the bullet would not rotate and it would be like shooting out of a smooth bore.

You can check this if you have a Lyman manual. Lyman always lists the "Groove Diameter" of all test barrels and firearms used. For example Lyman 48 page 216, 308 Win, Groove dia .308 inches.

EDIT:
Never mind, you are correct, I didn't read the "European" connotation at the beginning. By Bad!
shouldn't the groove to groove measurement be larger than the land to land measurement?
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Old 07-11-2013, 03:17 PM   #19
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Quote:
Originally Posted by mybigguns View Post
shouldn't the groove to groove measurement be larger than the land to land measurement?
Yes.
We measure from grove-to-groove, a 30 caliber barrel will have .308 inches.

Europeans measure land-to-land, a 30 caliber barrel will measure 7.62mm land-to-land and .308 groove-to-groove. 7.62mm = .30000 inches.
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Old 07-11-2013, 04:16 PM   #20
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Quote:
Originally Posted by mseric View Post
Yes.
We measure from grove-to-groove, a 30 caliber barrel will have .308 inches.

Europeans measure land-to-land, a 30 caliber barrel will measure 7.62mm land-to-land and .308 groove-to-groove. 7.62mm = .30000 inches.
European 7.62mm = .311 groove to groove (bore diameter)


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