Author Topic: COL Question  (Read 286 times)

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Offline benchmark

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COL Question
« on: December 02, 2019, 01:33:18 AM »
Regarding COL.  On the Western Powders tables it states the minimum COL, but not a maximum.  What is the maximum on 10MM?  I did not see it in SAAMI info either. 

On .45 I ended up just measuring some store bought Blazer Brass and found it to be roughly 1.27.  When reloading .45 I just split the difference and load them at 1.25 (min is 1.234).

Input?

Offline painter

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Re: COL Question
« Reply #1 on: December 02, 2019, 08:26:32 AM »
SAAMI says 1.250. CIP says 1.260, or 32mm.

https://en.wikipedia.org/wiki/10mm_Auto
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Offline tdogg

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Re: COL Question
« Reply #2 on: December 02, 2019, 04:34:06 PM »
SAAMI says 1.250. CIP says 1.260, or 32mm.

https://en.wikipedia.org/wiki/10mm_Auto

Saami states it at 1.26 inch Max.

https://saami.org/wp-content/uploads/2019/02/ANSI-SAAMI-Z299.3-CFP-and-R-Approved-2015-12-14-Posting-Copy.pdf

On .45 I ended up just measuring some store bought Blazer Brass and found it to be roughly 1.27.  When reloading .45 I just split the difference and load them at 1.25 (min is 1.234).
Input?

When performing initial load development with a new projectile, you should always determine the maximum overall length for your gun first.  Wobbly's excellent description is found here:  https://czfirearms.us/index.php?topic=103620.0  This will make sure you are loading in a safe regime for your pistol.  Essentially the load data gives you the minimum and your barrel (or magazine) gives you the maximum OAL.

You can verify your Push Test results by loading a dummy round at the chosen OAL and performing the Plunk Test (google it).  You can also perform the Plunk Test on purchased factory ammunition to ensure it will cycle in your pistol safely.

Please don't use factory ammunition to determine anything with your reloads.  There are way too many different bullet profiles out there (not all RNFP are the same etc...) and the tests to determine the Max OAL for your bullet/pistol are quick and easy.  If you run into a situation where the determined Max OAL is shorter than the published Load Data you are referencing, then post up a question here and the experts can chime in to help you reduce the starting load to keep you in a safe regime.

Cheers,
Toby




Offline painter

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Re: COL Question
« Reply #3 on: December 02, 2019, 05:29:44 PM »
I guess Wiki is wrong.
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Offline tdogg

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Re: COL Question
« Reply #4 on: December 03, 2019, 01:44:38 AM »
I guess Wiki is wrong.

Yeah when I saw that they were not stating the same max between CIP and Saami, I thought that is weird?  So then I pulled up the Saami spec and sure enough wiki does not list it correct.

Cheers,
Toby


Offline painter

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Re: COL Question
« Reply #5 on: December 03, 2019, 06:43:02 AM »
I edited the Wiki page.
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but not the ability.

Offline Wobbly

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Re: COL Question
« Reply #6 on: December 03, 2019, 10:18:16 AM »
Regarding COL.  [snip]  What is the maximum on 10MM?  I did not see it in SAAMI info either. 


• Many pages of load data simply report what OAL (aka COL) they used for the test. They are not recommending, merely making a statement. If you'll read Load Data as if it was a Test Report (this is what we did, and this is what happened), then it will make a lot more sense.

• As with all auto pistols, the maximum OAL is that which the barrel allows. SAAMI may have a number in mind, but that is usually what the magazine will accept. The realities of bullet-to-barrel fit are what truly determine YOUR Max OAL. If you have 2 pistols of the same caliber, then one may be more restrictive than the other. In that case you'd want to use the more restrictive of the 2 chambers as the Max for both.

• As with any new caliber or cartridge, you'll want to record this information you generate in your reloading notebook.


Being the most pressing need, CZ's 9mm chamber is what the "How to find Max OAL" article is based upon, but everything in it applies to auto pistol cartridges of ALL calibers.

Hope this helps.  ;)
« Last Edit: December 03, 2019, 10:23:39 AM by Wobbly »
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Offline benchmark

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Re: COL Question
« Reply #7 on: December 06, 2019, 07:33:42 PM »
Thanks all! :)

Offline noylj

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Re: COL Question
« Reply #8 on: December 09, 2019, 10:52:14 PM »
For the reloader, there are really no limits to COL other than:
1) ALWAYS work up the load from a safe starting load (which may be too low to cycle the gun, but you can watch out for such things as a bullet not exiting the barrel)
2) the COL must feed and chamber in YOUR gun (reloaders need not ensure that ALL their rounds work in all other guns in existence).
Per Ramshot (and all other reloading suppliers):
“SPECIAL NOTE ON CARTRIDGE OVERALL LENGTH (COL)
It is important to note that the SAAMI COL values are for the firearms and ammunition manufacturers industry and must be seen as a guideline only.
The individual reloader is free to adjust this dimension to suit their particular firearm-component-weapon combination.
This parameter is determined by various dimensions such as
1) magazine length (space),
2) freebore-lead dimensions of the barrel,
3) ogive or profile of the projectile and
4) position of cannelure or crimp groove.
• Always begin loading at the minimum "Start Load".
• Increase in 2% increments towards the Maximum Load.
• Watch for signs of excessive pressure.
• Never exceed the Maximum Load.”

Your COL (OAL) is determined by your barrel and your gun and your magazine and the specific bullet you are using.
What worked in a pressure barrel or in my gun has very little to do with what will work in your gun. Load a couple of dummy rounds (no powder and no primer) to the max. COL (OAL) and see if it fits your magazine, feeds in your gun, and chambers in your barrel.
Seat the bullet slightly deeper until you achieve all three of these goals. This is the COL (OAL) for you in your gun with that make of bullet.
For some bullets, a factor that will determine if the round will feed is when the magazine lips release the round. Earlier release is critical for JHP and SWC than for RN

 

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