Nothing wrong with a smaller groove diameter, if indeed that's what you have.  I very regularly shoot .308 bullets out of my Swiss K31.  It has a .294" bore and .3055" groove diameter and is perhaps the most accurate milsurp rifle I have.  The bullets will swage down to the diameter they need to, once the pressure starts rising.  I generally anchor the push out rod to the floor and hit the rod I'm pushing the ball in with so that the ball is smushed out into the grooves, making sure you get the full diameter.  You ought to be getting the full diameter with the .33" OO.