Every attack skill that isn't Artillery should have a star taken off in the recommended section, since affinity doesn't do anything for your shelling damage, and that's where most of the power comes from.

Seriously, if you're going to comment with "you need 3 pieces!" statement over and over, you may want to read up what safi's enhancement of Zorah Magdaros Essence is.

Seriously if you’re going to make builds and post them on this site, actually check to see if the skills you’re putting on the build make sense. Artillery 5 ONLY comes from zorah 3 piece bonus

Check the safi builds. You need the 3 piece zorah + bonus for artillery 5. As of right now it only shows the build with 2 pieces

I would take a good look at your versitile gunlance build, it seems full of errors.

Well by far gunlance have different type of shelling, so i think maybe there are several skill that unnecessary for jewel slot.

In your versatile endgame build for the gun-lance, there are some errors with the decoration slots. You don;t need all those artillery jewels and iron wall jewels.