SpudFiles

what would be better for a small bore qev gun. black iron or Galvanized fittings? there both about the same price

From a strength perspective, both are way more than strong enough to handle anything a QEV can give them. Both are heavy, black iron will eventually be more proned to rusting. Other than that, is really your choice.

galvanised... it won't rust...

though to be honest I have to say that galvanised fittings that you can buy these days are not as rust proof as they were in the past

I know that some of the black iron fittings I tried using on the pneumatic gun I built a couple years ago rusted very quickly and eventually started leaking. I'm assuming it is because the moisture in the air I was pumping in to the gun condensed as the air was compressed and deposited itself on the insides of the fittings. I ended up switching to brass. However, if what you are putting through the pipes doesn't have any moisture in it (like propane), black iron is probably fine. Other than that I would probably go with the galvanized to avoid rusting issues.

Black iron is a bit cheaper though.