Tortoguns are actually some pretty nice features in here with the ability to burst out high damage numbers in a brink of a second while giving you the ability to go on the highest distance amongst all other swords and guns into this process. Their shots and charges do never slow you down while reloading.

The downside is that it lacks of dps and that it requires training to get to know how to shoot. Also remember that it bursts out high damage with its charge and the 4* version of Savage Tortofist can almost kill a Trojans in D24 with one charge, but that it takes time to place a shot and thus its dps might be lower than other weapons.

I would myselfe call this weapon type as a highly agile weapon that is best used while running and dodging enemies and kill stuff that fallow you, rather than dash in and kill what is in front of you.

From my experience, are the specialized guns (green, purple, yellow) able to kill each small enemies with the charge attack, when 3 shards are hitting - which is the normal case if you know the monster AI.

Bigger monsters in the size of trojans, giant lichens or trojans are usually not be killed in one charge, but due to the big size of these monsters, they have a hard time with the shards that are stuck on the floor, since these shards can not be walked through by any monster.

And this is another aspect of this gun:
It is a completely unique feature that players can create something like a wall - and the torto crystals stuck into the ground are literally unpassable for monsters. So if two players spamm one clockwork path or the exit of a devility arena, then no enemy is able to get through it. Literally.

A good example for that path blocking mechanic is the right room of D26 FSC.
I am bringing my green 5* tortogun , enter one of these small rooms, and just spamm charges out of the room. Since zombies are so slow, they can not move fastly enough between two charges to get through this.

Two other good areas where these guns shine best are:
1. (Green variant) the first depth of the mission 'Ghost in the Machine' where many mechaknights, zombies and other stuff fallows you that you want to outrun when they come in crowds. Just leave a trail of green crystals on your way behind and watch the monsters get 1hitted one after another.
2. (Purple Variant) Deconstruction areas in which you often find yourselfe in beeing chased by gremlins with a healer in the back row. Just pul out the charge and walk away and time your charge so that the the crystals come down when the healer is below the shards - or just nuke the group of gremlins that is chasing you since one charge always kills a few gremlins at once, when there are enough together ;)

The red tortogun is a gun I would recommend last because their crystals are not powerful enough to kill small enemies with only 3 hit crystals. It is a nice gun to test the mechanic itselfe, but it is far away from doing wonders. If you see the gun as pure utility though, then you may like to plant a safe spot made of crystals into an arena or simply to hold a group of enemies back for a moment - just to charge another weapon and unleash it from the other side of the crystal wall, that only monsters can't pass.

If you have a specific question though, just ask ahead :)