Weapons aren't good or bad in isolation. Weapons are good or bad in certain weapon-sets and in certain situations. An obvious example is Warmaster Rocket Hammer (great weapon) and Nova Driver (great weapon) in a wolver den (terrible loadout). So what other weapons do you plan to pair with this new gun?

If you don't know how to answer that, then consider this: What niches are unfilled by your current weapons? Do you have a shadow gun? Do you have a big normal charge attack weapon for those few places in the game that favor normal damage?

I kind of think that everyone should be crafting a grim repeater. It's just got too much potential against construct etc. and the bulk of players are going to have to learn that play style anyway when they go to FSC and get a blitz needle so that they can be cool (and absurdly effecitve....) like all the other FSC players.

Volcanic pepperbox is also a super fun get and I'd recommend it any day, it's just not quite as earth shattering as grim repeater.

It sounds like your problem isn't getting a gun but getting better at dealing with jellies. A good shield is key to fending off spikes, for the cubes keep your eyes peeled when they do their ranged attack to see where the spikes will come up (or just shield when they do it), keep your distance from lichens and be sure to shield bump them away. You just need to keep your eyes peeled for their ranged attacks and you should be fine. I ran through most of the game with little help using nothing but a Blaster (that was before we had type damage blasters BTW), I have even soloed T3 slime danger rooms with just a Valiance. Good shielding skills and good responses is key in this game, especially if your damage output isn't great enough to gun stuff down before it reaches or shoots you.

I would suggest getting both these guns but more importantly I would suggest you practice more against slimes. Keep going till you can solo floors without taking damage at all.

I have no beef against Grim Repeater, however for what it's good against you either don't really need it, or simply would be better off with another type of weapon altogether. Jellies are relatively easy once you get their rhythm down with any weapon, and gremlins usually require mobile/swift weapons to dispose of easily unless you're relatively good at the game (and that this point there would be no need for high-powered weapons to take them down).

Volcanic Pepperbox is an all-around good utility weapon for dealing a good amount of damage, high DoT status-effect, respectable knockback from its charge, and global damage since it's normal. There would be little reason to not be holding onto this gun unless you either get bored of guns or feel the need to change to a more situational piece of equipment.

Grim Repeater has a little bit more damage than V.Pepperbox, but lacks status effect. Knockback on charge still applies, however it's only strong against 4/6 enemy types as it does Shadow damage (Undead are also a piece of cake, fiends not so much). You can carry the weapon with you to almost anywhere, except probably undead/fiend levels. So there's that.

Alternatively, I could also vouch for Blitz Needle if you end up getting Grim Repeater to complement both strengths and weaknesses of each one, Blitz being the more famous line due to its superior usability in FSC (among other places as well).

But all that's just my opinion.

Dutch you forgot Ghost in the Machine. Undead+Construct, pepper box wins

Don't even need a weapon to kill bombies. I don't think mecha knights total hp would be huge enough to make pepperbox inferior compared to grim.

Hey I know it works, it's just other things work better. The rooms in Gitm are really not suitable for autoguns. It IS a good idea to take an autogun for the boss, but blitz and grim are actually better than pepper for that so.

I didn't put GitM on my list because no autogun is best autogun for that mission. I use drivers and mixmaster personally.

(seriously what knight would try to kill mechas at long range?)

I've gunned mechas before.. you just have to wait for them to commit to an attack before you blast them. Or you can use mixmaster, and they won't know to shield. The same goes for the tortodrone guns, due to the period of time where they wait about doing nothing when you shoot.

The rooms in Gitm are really not suitable for autoguns.

Pepperbox is actually quite potent in GitM- the zombies are weak to fire, the deadnauts leave their backs open all the time, the turrets fall easily to autogun charges and even normal hits, and it works well on the boss as well. Grim repeater/blitz would be better for the boss but not THAT much better.

Of course saying that pepperbox is better/more important than grim repeater because of that one scenario is kind of nuts, especially since by that point in the game you probably have several elemental weapons that would handle GitM just fine..

(seriously what knight would try to kill mechas at long range?)

hit them with a Combuster or Obsidian Edge charge.

Um, What?

Autogun charge works exactly the same like brandish charge in that case, holy-nightmare.