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Wyoredman - I basically use the same idea but a different method. Starting with five fired cases, I tension the case mouth enough to slightly grip the particular bullet I will be loading. The cases and bullet are inserted into the pistol chamber and pushed forward until the bullet contacts the lands and the case headspaces in the chamber. The bullet will get pushed into the case. The case and bullet are removed and the length is measured. This process is repeated until I'm confident I have a good OAL. For jacketed bullets I use finished OAL 0.015 shorter to get achieve the setback I want. For lead bullets, I may actually seat at the lands, but that's a different animal.

Grandpa45, the information I'm quoting is something ALL handloaders should know. The method I use and recommend is very similar to what serf 'rett is recommending. With 9mm jacketed bullets that have the correct diameter of .355", I use Winchester cases where there is enough tension between the bullet and case that you probably won't have to add additional tension. Just start the bullet into the fired case and place the "dummy" into the chamber and push on the rim until the case stops. That's where the case-mouth is contacting the forward ledge in the chamber and the barrel's leade/throat is seating the bullet to give you the MAX. allowable OACL. Obviously, the round has to be short enough to function in the mags. Make up 5 "dummies" so that you can compare the consistency in OACL between the 5 "dummies". In situations where the bullet is slightly over-sized, you may need to tap very lightly on the case-rim with a plastic mallet or a block of wood to fully seat the case. Depending on the OACL tolerances of your handloads, controlled by your press and dies, your loaded cartridges should be .005 - .010" shorter than the Max. allowable you got from the average of the 5 "dummies".

Naturally, there are exceptions. In your case, your press/dies are varying too much in OACL to use even the .010" shorter recommendation. Having loaded a lot of 9mm over the years, I have used my fair share of European powders where OACL recommendations will sometimes be in millimeters, sometimes both inches and millimeters. What I do today after finding the MAX. allowable OACL is to shorten my handloads by .5mm. I load my own defense loads and maintain very close tolerances in OACL because the majority of my loads are +P, at least in terms of the velocity they'll achieve. The majority of these loads get loaded on a single-stage REDDING Boss with REDDING dies. The Boss has a feature called Top-Dead-Center that helps with OACL consistency. The only real OACL variations I get come from the bullets themselves, but typically with the JHPs I use for my defense loads I can hold a tolerance of +/- .002". For my 9mm pistols and those of my shooting partner whom I also load for. I load JHPs to 1.142"/29mm. There are a good number of 9mm pistols that have throats that are too short for this OACL. In that case I drop down to 1.122"/28.5mm. There are very few 9mm pistols that won't accept and function with that OACL. In the case of a particular bullet's design or a very short barrel throat, 1.102"/28mm will work. For 147 gr. JHPs as well as various weights of FMJ, a longer OACL is often desirable. Again, after confirming the MAX. allowable OACL, I load long at 1.161"/29.5mm. That may be too long for some 9mm pistols so you can see the necessity of determining the proper OACL for an individual bullet to be fired from an individual pistol.

The 1.155" you lengthened to is pretty typical for 115 & 124 gr. FMJs, but that should be at least confirmed by a "plunk test" or better still, by making up 5 "dummies to determine MAX. allowable OACL for that particular bullet.

serf 'rett caused me to consider an example of where adding a little tension to the "dummies" could be very useful. I have some Montana Gold 124 gr. JHPs and they are slightly under-diameter with a good many of them measuring .354" in diameter, so adding some additional tension may be necessary to hold the bullets in place firmly enough for measuring purposes. There is also a reverse condition that can occur with pistol barrels that have tight chambers. If the case-mouth diameter on your "dummies" run higher than the SAAMI Max. spec of .380", the cases will not easily seat and too much force from tapping will be required. This will often result in the bullet becoming lodged where you'll need to use a dowel rod from the muzzle to tap the bullet out and that's gonna result in the bullet being seated deeper into the case. To avoid this occurrence, taper crimp the "dummies" just enough to get the case-mouth under .380". So long as you don't over-do it with adding taper crimp, your pulled bullets from the "dummies" should still be in pristine condition for reloading.

I didn't see it stated so I'm surprised this wasn't mentioned. To maintain somewhat of an equivalent pressure between 2 bullets of the same weight but with different lengths, you could have added the extra bullet length of the longer bullet to the OACL recommendation of 1.125". Determining the exact length for the bullet you're using is still preferable and would have given you a longer OACL than adding the additional bullet length to the 1.125" OACL. In 9mm, all I load are JHPs, but the OACLs most often recommended for safe and accurate FMJ loads are around 1.150" give or take so I'm guessing that someone recommended the 1.155" OACL you lengthened to.