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Old September 29, 2002, 07:39 PM   #1
Gary H
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What is C.O.L. ?

I would like to correct and refine my understanding of this term and it's application.

Reloading manuals list Maximum C.O.L., Maximum Cartridge Length, or O.A.L.. Since bullets come in various shapes, this measurement must constrain bullet length in order to prevent the bullet tip from encountering obstructions due to excessive length. This maximum is set by SAMMI, but does not represent the true maximum, nor the optimum overall length. Having said that, Stoney Point and others market gauges for measuring Overall Length. These systems are somewhat cumbersome and bullet profile dependent. The exact measured length of a particular seated bullet that just touches the rifling is totally bullet profile dependent. Adding a device to measure off of the bullet's Ogive simplifies things in that the distance from the bottom of the case to the Ogive will remain constant from bullet to bullet when determining the longest cartridge that fits a particular firearm.

To bring this back to a practical level. It seems that for most pistol cartridges it is sufficient to establish a measurement based upon the length of the bullet/case. Rifles and some pistol applications, where greater long range accuracy is required, measurements based upon bullet Ogive provide more consistent results when working up differing loads using various bullet designs.
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Old September 29, 2002, 09:21 PM   #2
Gewehr98
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Umm...

OK! (I guess?)
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Old September 29, 2002, 09:41 PM   #3
Johnny Guest
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Yup - - -

Agree with Gewehr98 completely.

C.O.L. is Cartridge Overall Length. But you knew that. Sounds as if you answered your own question in more detail that most anyone else would have done.

While what you said makes sense within the context stated, I kind of believe C.O.L is normally stated (and standardized by SAMMI, etc.) fo that excessive length will not be a problem. Certain rifle cartridges--.257 Roberts and .350 Remington Magnum come to mind - - - are frequently capable of more efficient performance if loaded out a bit, but magazines of some rifles will not allow them to funciton at greater-than-standard length.

Some revolvers have cylinders which will not allow for crimping certain bullets at the canelure or the crimp groove. And, of course, some bullets, though of the right diameter, are not usable in some autoloading pistols due to magazine length and/or feed ramp geometry.

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Johnny
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Old September 29, 2002, 09:55 PM   #4
Gewehr98
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I've answered my own questions several times, myself!

Of course, I'd pretty much forgotten why I asked in the first place.


Where C.O.L. can really mess up one's gray matter is when a company (let's say Remington) chambers their rifles (let's say a 700 PSS in .308 Winchester) with throats so long that the bullet won't seat with more than 1/10" in the case neck when it's close to engaging the rifling. Good, accuracy is wonderful! Then the damned rounds won't fit in the rifle's box magazine.

I gave up and just seated the darned things to fit in the box magazine. Accuracy is still pretty darned good, but that bullet jumps quite a ways!
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Old September 29, 2002, 11:39 PM   #5
C.R.Sam
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Then there are the folks that like a lot of freebore...
Roy Weatherby etal.

I just fiddle with em till they work.

Sam
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