Curious to how much variation you are seeing in OAL when loading 9mm. Please specify what type of reloader and dies you are using. I am seeing plus or minus .002 using a dillon 550B and Lee dies. I measured every fifth round out of 100. Berry's 147 g.
I set it and forget it.
Sorry I know that is not the answer you are looking for but pistol rounds are not as fussy as rifle as far as accuracy is concerned.
Shape of the bullet and consistency of brass and use of the press will affect things some. However 002 that is really good if that is what you are getting
my 4 cents
.002 isn't anything. I am surprised it is that little. They must be really good bullets. I am used to .010 to .015 with Rem and Win bullets. This much doesn't matter either.
For me OAL lenght is more determined by the bullet profile and type of gun. Most ball ammo I've encountered is fairly "pointy" compared to the blunt cast lead Lee 125 I use fairly often. These have to be set deeper to keep from engaging the rifeling before full chambering.