I noticed many reply's to forum questions giving the bullet grains and powder grains and powder brand with no mention of C.O.L - as a newbie i understood that if you press say a 9mm in to far - even .003 you could cause major pressure issues- i hope i'm right in setting the COL so accurately as i spent a fortune in calipers and micrometers

I think if you follow published loading day your going to fine.

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Bob from Idaho

As you can see, I didn't get much response when I posted a similar question earlier. It must take a ballistics engineer to answer it since there are so many variables, but I have observed this. Out of the gobs of loading data I've examined, most for .40S&W, I have yet to see a cartridge loaded to the maximum COL or even .005 less, so if you load between .005-.010 less than max you'll at least be safe. All you can lose is maybe some velocity and a little accuracy and how much would it matter at 50ft. or less?
Mike

Note that the manuals give a starting load. Thats to allow for differences in components and guns. Theres also a COL usually listed with the data. Bullets vary a great deal in nose design so they might need a less than max length. For an autopistol you may have to vary that length to get a particular bullet to feed correctly in your gun. The max length may be exceeded but will still function ok. Revolvers are different and COL often exceeds the max COL listed with some designs, mostly with cast bullets. As long as it doesnt stick out of the cylinder it should work OK.