We've discussed pretty much every aspect of every handgun in the last few months and the general consensus has been that catalyzer is garbage and that pulsar is better but really only suited for some higher level play if at all.

If you're new to the game and going gunner, you should be probably be looking into building a charge time reduction build consisting of chaos + seerus, with drivers and autoguns as your main weapons. The benefit to using these is that they provide loads of damage both close up and at a range, and become vastly more powerful with your experience using weapons as well as when given the now common handgun boosts associated with the above chaos+seerus combo.

Polaris/Supernova/Wildfire/Permafroster do not do these things to nearly the same extent and typically cap out on power much faster- once you can hit an enemy into a wall and blast it, you can't bolster your attack in any way except via applying damage ups, which also do less for the guns (15 hits on blitz vs 3 hits on polaris). This leaves you with a more narrow skill ceiling, and makes the gun less worthwhile.

The big redeeming factor for pulsar lines is that they start out fairly strong and don't require any additional buffs to be useful. This means that you can stick them onto whatever loadout needs them, and fire away to flinch/knockback crowds of enemies. The problem here however is that the levels that benefit from being able to do this are far too few and there are almost always situations that will render your pulsar useless by forcing you into a tighter area. Because of this, pulsars are largely unnecessary and only really optimal towards the end of the game when you can afford to craft one entirely for those situations to improve your play just a little bit more.