Threat to the West, Rundall EX Quest

If you are needing the gun recipes, do multiplayer farm. It drops 2x at a time instead of one for single player at half the energy cost or free.

The recommended level is 50 but even with a full party around that level they still get torn apart because the gunners get a ton of hits that make chains before most units can approach and those fast enough to do it aren't tanky enough to survive the focused firepower more than 1 turn. This map is just designed to tear you a new one if most of your units aren't strong and enough to 1shot the gunners on the first turn.