Optimal COAL

[Donny1]

How do you determine the optimal OAL when working up a particular load?

I recently took various 9mm loads out and ran them through 3 guns and all the chrono data showed me I need specific loads for each which wasn't any surprise. Going from pistol to pistol is not so dramatic but 3 or 5 inch to 17 inch barrel is something else entirely.

What are you looking for to get the optimal OAL, longest you can get that fits the mag? A Certain seating depth? Or just something that feeds reliably. The exact data for every combination of bullet and powder realistically doesn't exist so learning this is key for me.

When I can't find the bullets I'm used to getting there is always adjustment for something different, I have mostly adjusted the seating depth to be similar for the same weight bullet and it's worked well and chrono data is very close to the previous load.

[RandyD]

On a 9 mm handgun cartridge, the cartridge seats on the rim of the case. If the cartridge case has been trimmed too short, you may experience the round not firing because the primer is not within the area where your firing pin is not striking it hard enough to reliably ignite the primer. I would not trim my 9mm brass any shorter than SAAMI specs, which is 19.15mm.

['ol shooter]

I load them to book specs, if they feed fine I run with it.
Any 9mm or .45acp case I have that would need trimming is turned into a keychain fob or in the round file.
ain' nobody got time for that.JPG

[sofbak]

Read the OP three times. OP asked about COAL, but both responses above talk about case length and trimming-what am I missing? (??).

Not sure there is an optimal COAL for pistol rounds. I always load to minimum specified length in my manuals and back it up with the plunk test. I learned the hard way that all ogives are not equal, and the plunk ensures my rounds will chamber.

YMMV

[Donny1]

Read the OP three times. OP asked about COAL, but both responses above talk about case length and trimming-what am I missing? (??).

Not sure there is an optimal COAL for pistol rounds. I always load to minimum specified length in my manuals and back it up with the plunk test. I learned the hard way that all ogives are not equal, and the plunk ensures my rounds will chamber.

YMMV

More like no ogives are equal.

Interesting, most things I've read say start at the max and work back from there, but I see no advantage to that unless you want to use more powder. I'm actually shortening the 124gn HP by .010 each time out for the M&P Shield because at "never exceed" charge it's still a bit slow, but it is a 3" barrel. I'm at 1.120. The CFE Pistol is listed as slower than other popular pistol powders in the charts, maybe I need a faster powder for the Shield.

[J-cat]

One should use the most reliable and accurate coal, not sone arbitrary book number.

[Donny1]

One should use the most reliable and accurate coal, not sone arbitrary book number.

Very true, unless you have the exact bullet they used it is arbitrary.

[Paseclipse]

One should use the most reliable and accurate coal, not sone arbitrary book number.

^^^ This

Interesting, most things I've read say start at the max and work back from there, but I see no advantage to that unless you want to use more powder.

OP, I'm curious to know where you read this information? Starting at maximum with almost anything involved in reloading is asking for a blown up gun or some missing fingers eventually. If anything, when working up a load it should be exactly opposite of this.

[Donny1]

^^^ This



OP, I'm curious to know where you read this information? Starting at maximum with anything involved with reloading is asking for a blown up gun or some missing fingers eventually. If anything, it should be exactly opposite of this.

Max OAL, not charge.

[Paseclipse]

Max OAL, not charge.

Oh, okay. Makes sense now.

Your best bet is to find an OAL that works in all your guns. Especially if your loading for a Shield, because they seem to have a tighter than normal chambers. If you found an OAL that functions in yours I'd run with it.

Optimal COAL is something that can help with accuracy for rifles. I'm not so sure about this with handguns.

[Donny1]

Oh, okay. Makes sense now.

Your best bet is to find an OAL that works in all your guns. Especially if your loading for a Shield, because they seem to have a tighter than normal chambers. If you found an OAL that functions in yours I'd run with it.

Optimal COAL is something that can help with accuracy for rifles. I'm not so sure about this with handguns.

Never heard that but it's eaten around 4-5k rounds with only 1 FTE on the first box, otherwise flawless. I think I do load on the short end but that's more a product of seating depth.

[fnlrun]

I loaded up 1000 rds for my Hellcat in 9mm. Not 1 would cycle. My shield eats them up no problem. I now plunk test everything for my Hellcat and it cycles through everything. Not all barrels are created equal

[sofbak]

"...some arbitrary book number."

That has to be one of the most moronic statements ever entered into a reloading forum.

[J-cat]

Lol, please explain yourself.

[sofbak]

Lol, please explain yourself.

OK. The explanation is rather simple, and interprets the information provided in (most?) reloading manuals-at least those that I own. As follows:

If you look at the load data tables, there is presented 11 different columns of data for each load "recipe" of bullet, powder, etc. And only THREE of the columns of information presented carry an implied, or identified qualifying adjective. Those three pieces of information are:

START (or) MINIMUM Load
NEVER EXCEED Load
MINIMUM COAL

So, it begs the question: Why are these three pieces of information (only out of 11 pieces of load info presented} prefaced by somewhat "restrictive" adjectives-Start, Never Exceed, or MINIMUM? The answer is that each one of those pieces of load information are critical to safe reloading, and wandering outside the limits identified by those adjectives could result in a "bad day" at the range.

So, WRT to the subject of the discussion, and the context of my statement on loading to the MINIMUM specified COAL, I simply do not consider that specified data-i. e. the minimum COAL to be an "arbitrary number from some book". It was published with the background/foundation on considerable analysed, test and measurement, and evaluation of data. COAL is hardly an "arbitrary number".

And to deviate beyond the specified limit(s) presented in a reloading manual is asking for trouble at the range.

YMMV