OAL? COAL?

[Rugerdaddy]

Being new to reloading, I have so far only purchased two books to learn from: The ABCs of Reloading by Chevalier. and Lyman's 49th Edition. I am learning a great deal.

However, as I began looking at load data in Lyman's I see two acronyms that I can find no definition for. I looked through both books (though I may have missed it), and I searched this thread but couldn't find the answer in either place. I can guess, and my guess may be right, but I'd prefer to ask you experienced loaders what they mean.

OAL and COAL? If they are what I think they are, why would they vary when using the same cartridge and bullet but different powder/load? Thanks for your help.

[bumpo628]

COAL = Cartridge Overall Length
OAL = Overall Length

Same thing; it's just an abbreviation of an abbreviation.

[Rugerdaddy]

Excellent! That's what I thought.

So, why would the length of a cartridge vary if the case and bullet are the same? Is it because different powders need varying amounts of space inside the case to burn correctly? I would previously have assumed that ALL 9mm cartridges have to be the same length to feed and lock in the breech properly.

??

Thanks.

[Noonanda]

Excellent! That's what I thought.

So, why would the length of a cartridge vary if the case and bullet are the same? Is it because different powders need varying amounts of space inside the case to burn correctly? I would previously have assumed that ALL 9mm cartridges have to be the same length to feed and lock in the breech properly.

??

Thanks.

it varies when the Bullet is not the same weight and shape. for example(using rough measurements just to get the point across) .308. a 110 gr round nose bullet is about 3/8 to 1/2 inch long, whereas a 150Gr FMJ bullet is between 3/4 and 1 inch long. when I load these 2 bullets into a .308 casing I am going to obviously get 2 different COALs. Bullet weight will dictate bullet length

[ocabj]

I personally use COL = Cartridge Overall Length

OA shouldn't be Overall considering Overall is one word.

[GeoffLinder]

There is no such thing as a "specific" OAL for any specific bullet weight or style. The truth here is that there is a range that works. Typically JHP will load at a different length than an FMJ of that same weight but not always.

An example is 9mm (9x19 parabellum). Published specs usually show 1.110-1.125" OAL's but in reality you can load from just under 1.110 to as long as 1.120" depending on the depth of magazine so they fit.

Generally it is best to load on the long side compared to minimum specs to start (1.135" to 1.145" for 9x19 as an example) to keep pressure safe and then change OAL if needed for function and accuracy reasons (too much details to go into on that here).

Hope this helps.

[Rugerdaddy]

Great information from all of you. Thanks.