I'm inclined to think 2.3mm might be a little big for primers but works well for sprayable fillers.
Most primers will go on with anything from 1.4 to 1.8mm.
Check Sharpe's website and look at the gun setup reccommendations per paint manufacturer. P-Sheets for intended products will also give you a good idea.
Good score, I've been looking at maybe getting a Colblat off of Ebay (as they seem to be listed almost all the time NIB). Not sure where I want to go with two new guns (primer and clear) yet.
Thoughts and comments expressed by me are mine based on my own experience and research and shared here freely. I am not a professional nor make any claim to be as such