Theory #1:
If the barrel is slugged at .357", you may need a .358" bullet to properly obturate.
Theory #2:
Too much crimp.
If you are using a crimp die in a separate step, try removing that operation from the equation.
Load a dummy round (no powder/primer).
Set the oal where you think it is right, i.e. 1.125 1.135 etc.
Without running it through a crimp step, try the plunk test and drop the round in the barrel chamber and see if it seats fully or hangs up. If it hangs up, apply only the slightest amount of crimp and try again. Repeat as necessary until the round drops easily into the barrel. I add just a hair more (crimp) adjustment to the crimp die to ensure even crimping with brass that may differ in oal.
A 9mm doesn't require a crimp so much as a "de-flare" to removed the belling created before seating the bullet. A friend of mine only flares the case barely enough to start the bullet and doesn't even use a crimp die.
If the crimp is excessive, it could be swaging the lead into a smaller diameter allowing propellant gases to escape beyond the bullet melting lead in the barrel at the throat until it reaches a point of obturation. I am not an expert by any means but I kinda sorta understand obturation. It is what happens when the lead bullet is slightly larger than the bore diameter and the propellant gases cut into the lead at just the right pressure to allow proper bullet to bore seal. If the pressure is too great, or the bullet too small (possibly from over crimping that would squeeze the bullet smaller) the hot gases go beyond the bullet base and deposit lead into the throat of the barrel.