9m luger coal issues

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Cjsva

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the guide i use is the sierra reloading manual, 5th edition. the first page for every caliber includes test specifications and the following pages go into details of powder loads and coal for different bullet grain and style. for 9m luger 90 grain jhp the coal is 1.010. the test spec coal for 9m luger is 1.169.

is the test spec a maximum coal?
is the coal for each grain and bullet style a minimum? or what?
 
Cjsva said:
the guide i use is the sierra reloading manual, 5th edition. the first page for every caliber includes test specifications and the following pages go into details of powder loads and coal for different bullet grain and style. for 9m luger 90 grain jhp the coal is 1.010. the test spec coal for 9m luger is 1.169.

is the test spec a maximum coal?
is the coal for each grain and bullet style a minimum? or what?
Click to expand...

1.169" is the maximum COAL for the 9mm cartridge.

The COAL for each grain is the 'test' spec they used for developing their load data for that specific bullet.
 
The max COAL (CARTRIDGE OVERALL LENGTH) is an industry standard developed with the standard style & weight of bullet when the cartridge was created. Lyman calls this length, loaded length w/bullet.

The spec is intended to be the maximum length round that will fit, feed, and function through all regular guns in that caliber.

Shorter rounds do work, and all factory rounds are a least a couple thousandths shorter than the max spec length.

Now, when you see a load like a 90 gr 9mm, with a shorter COAL listed than the standard 1.169, (which was based on the longer 124gr/115gr bullets) all it is telling you is that is the length that the shorter, lighter bullet resulted in.

Remember that the amount of the bullet inside the case is nearly always close to the same when the bullet you're looking at is lighter (and so shorter) so the total loaded length of the round is less.

The numbers are not something you have to load to, its either the industry standard max or its the actual result of loading a shorter bullet.

Bullet tip profile also makes a difference in actual measured length, because we measure overall length from case base to bullet TIP.

For example, take two bullets of the same weight, say 115gr 9mm, one a pointed FMJ and the other a JHP. With the same setting on the seating die stem, the pointed FMJ will measure a bit longer than the JHP because it has a projecting tip the JHP bullet lacks.

And, while the bullet tip doesn't touch anything when the round is chambered, it is something that can matter when feeding through a magazine.

Some guns have magazines that have enough of a slope to them that a "too long" round (and again base to bullet tip) can fit and feed as the top round or two but that same length deeper in the magazine body can bind.

Anytime you're working with "long" loads (close to max length) it is wise to completely load the magazine and see if they function properly from all the way down to the top.

The max listed length for the round is not something you have to achieve when loading, it is something to pay attention to not exceeding. Some guns will function with ammo slightly longer than the max spec, many, if not most will not.

Testing your individual gun is the only way to know for certain.
 
However, you should do the plunk test to see if that COL will fit in your barrel. Remove the barrel from your pistol and drop the loaded case into the barrel. If it spins easily that should be a good COL for your barrel.
 
Most factory ball is around 1.135 and not 1.169 which may not fit in your magazine or chamber smoothly. Measure some factory ball and compare with what you are loading.
 
Also know that you'll want to be consistent with your COL for each specific bullet type/style as varying COL will result in changes in pressure.
 
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