Attack overcomes Defense. Higher level enemies have more defense. To get a [b]rough [/b]idea of what's going on, divide your Attack rating by 10, and your weapon will be doing max damage against that enemy (ex: Attack 300 weapons are doing their max damage against lvl 30 enemies, whereas Attack 331 weapons are doing their max damage against lvl 33s). Impact determines baseline damage, which is then affected by Attack and your level vs. the enemy level (if you are a lower level, you do less damage. You do not do extra damage against enemies you are higher leveled). This goes both ways, which is why you can take a lot more punishment from lower level enemies. Attack is not the end all, be all. Ask any raider, and they'll tell you that Fatebringer and VoC are viable, powerful weapons, even in hard CE. Makes sense? Clear as mud? Re: edit 1, I believe in your example, they would do the same damage per bullet. For primary weapons, it seems that impact is a reliable indicator of damage relative to the other primary weapons. For some reason, this is not the case for secondary weapons.