1.169"
This is the listed maximum 9mm Luger loaded length. Any round loaded to this length, or less should function through any SAAMI spec pistol.
Should. HOWEVER, the spec dates from a time when there was only one bullet profile factory loaded in the round. Both the 124 and 115 bullets feature long tapered ogives and are more pointed than many other "RN" bullets.
TODAY there are many different bullets with different nose profiles, so going just by COAL max length is no longer a guarantee the load will function at that length, if the bullet used has a significantly shorter, "fatter" nose section than traditional FMJ slugs.
Yes, we all use COAL because it is a simple measurement, and consistent, for each bullet type/style a change in the COAL indicates an equal change in the amount of bullet inside the case. (seating depth)
Where you can run into trouble is loading different styles of bullets with the same COAL and expecting the seating depth to be the same. Consider spitzer and RN rifle bullets as an example. Same bullet weight, but the RN is shorter and fatter, so if you load both to the same measured overall length, you get different amounts of bullet depth in the case.
When you load both so the same amount of bullet is in the case, the COAL will be different. As long as you understand that, (and why) its not an issue.
The same applies to pistol bullets, but the difference is not quite as obvious and easily seen, most of the time.
IF the OP is doing what it sounds like he is doing, loading his particular bullet so long that it hits the rifling before the case is fully chambered (something no gauge can tell you) then he needs to seat it deeper, experimenting in small steps until he finds the depth that will keep the bullet clear of the rifling.
THEN he needs to work up his powder charge to what he desires with that bullet at the COAL that will chamber in his gun.
All guns are not equal, despite SAAMI specs, and as noted, some are "notorious" for short throats.
Friend of mine once had a couple of (modern) Walthers that would not chamber Cor-Bon 9mm ammo. The guns worked with everything else he tried, and Cor-Bon worked in the rest of his 9mms, but in those two the throats were too short for that ammo.
The only gauge that matters is the gun you are using. Max listed COAL is not a goal to be reached, its a limit to be avoided, most of the time. Some guns will take ammo loaded longer, many will not. The point is to make ammo that works in your gun, and if that means loading shorter than listed max, that's what you do. How much depends on your gun and your bullet.