Learning to paint....

I would look at the manufactures needle size recommendations for that epoxy. Normally epoxy is pretty thin and is shot with something closer to 1.4. Going up to almost 2.0 seems way out of line of any epoxies I've read about so far. But each manufacturer is different. Usually you can find the answers on auto body forums if the manufacturer makes it difficult to find.
Epoxy is not a primer. A larger tip would be for heavier bodied sandable primer. In the old days we used epoxy for a sealer with a little thinning and to protect bare metal .