I need a new gun. Help me pick!

Yes. This one of those "I'm an incompetent knight and I need help wiping my metallic buttocks." Kind of thread.
So if you didn't know that first hand from the title at dealing with with me...there you go. Some fair warning.
I'm a three year old 4 star sworddancer. I've been using a grand flourish and an ascended caliber, and recently broke my arm for a silent nightblade from a very crass individual. (My brother.)
My armor is Ashtail gear. And my shield is a swift buckler.
So...it's quite obvious that my use of guns is...barebones at best.
which has been only one gun. A master blaster.
My blaster has mainly been used as a utility type of device. hitting switches and out of reach warp boxes.
Sometimes even being used as a emergency weapon when my health is low.
...I have trouble aiming at moving targets.
It's about time for a new gun.
And I'm hoping for some recommendations.
Or, maybe you could enlighten me on some potential choices I'm thinking about.
A pepperbox, a needle gun, or a shock pulsar line.
Much love will be given by me to you for helping me! Thanks!

A pepperbox, a needle gun, or a shock pulsar line.
How did you pick those? Autoguns fill an entirely different role from pulsars (massive-damage charge attacks vs. crowd-control regular attacks).
Have you read the Gunslinger Guide on the wiki? It's not great, but at least it can give you some more specific ideas.
Are you planning to keep using one sword and one gun? Then you might consult the Mixing Weapon Types section of my detailed sword guide. For example, you might work on Final Flourish, Acheron, and Nova Driver or Iron Slug. You could make several great loadouts by combining two of those.
But if you have trouble hitting moving targets...then I would suggest practicing.
But if you still can't hit moving targets (maybe because your computer/network is not great) then get a pulsar --- anything but Permafroster, whose freeze contradicts the point of pulsars.

"I have trouble aiming at moving targets"
If you currently have trouble aiming with a master blaster you definitely need more practice. That gun line has one of the largest hitboxes.
Personally, I'd only recommend a different gun after you have more skill with aiming. The magnus lines are very lethal, but only if you can carefully line up shots.
If you want a solid gun for not-fast-moving targets (constructs/undead), go for one of the elemental drivers (alchemer line). Other players like pulsars, I'm not much a fan of them because they don't work well in teams often.

"-Revolvers in general, whether they be Pierce, Elemental, or Shadow
...What? Do you mean Blasters?
I didn't really read that in detail, skipping around a bit, so I might have missed it if you put the correct name somewhere in the post, so sorry if you did and I missed it.
Either way, you should edit your post and correct that.

I picked those because I felt they would be useful in the long run and I was a bit interested in them.
I understand they would work differently but once again, it was a matter of interest.
I did read your guide, very helpful.
So I suppose I fill out the requirements of shadow and piercing with normal.
But I definitely need an elemental sword...Voltedge sounds promising.

I'm glad that you found my guide helpful. I hope that you have also found the Gunslinger Guide helpful.
Voltedge is great, although usually not quite as great as Combuster, as my guide explains.
Your self-assessed inability to hit targets is a much bigger problem than damage type. As posts #2 and #3 remark, it takes practice. Certainly you will not be able to use alchemers or magnuses --- two of the most impressive gun styles --- if you can't aim well. You will be able to use autoguns, but those come with other problems (less mobility, more boredom).
Good luck.

So far SkepticRaven has the best advice- if you can't hit things with your master blaster, you're not going to have a good time with most other guns. It would be feasible for you to craft a blitz needle and use that in close range, but you probably haven't mastered enemy AI well enough to pull this off and your sword charges basically fulfill the same function of hitting trojans/deadnauts in the back but not as well. Pulsars would allow you to hit things far more easily, but would become frustrating at close range and don't deal enough damage to warrant slopping enemies everywhere unless you know what you're doing.
Another thing that hasn't been brought up is that pulsar damage expanded = valiance damage always, so don't think that you're getting more damage out of that explosion.
@What sword should OP craft next?
The only difference between the brandishes is their charge (and acheron's damage). If you don't have charge time reduction it doesn't even matter which brandish you choose. I'd personally have you craft a divine avenger, so that you can use the normal hits on vortex'd enemies and on multiple enemies at a time.
Also triglav. I want a ton of knights using triglav because that would be fun for me to watch. Admittedly this is probably not a good enough reason for you to craft it unless you're awesome.

by reading till now, i would say that Soupgeni has the best detail overall in weapons, but I want to proceed with some details:
------- Pulsars -------
Bad in aiming:
First that came into my mind were pulsars. You just can spamm them and they will ripp monsters to death, but only as long as the come from one direction like in clockwork tunnels.
For beginners, this weapon can be unrelieable, when monsters come too close and you can not get the bullets expanded to get its knockback. This means: in an arena you need to define a corner in which all monsters should go. Once you decided for a side and you do not get backstabbed, you have almost nothing to fear if you can just keep spamming bullets.
Choosing a pulsar:
This is a point where I need to object to what Bopp said. It is true that the shadow-freeze pulsar does not push enemies away as quickly as the other 2 variants, but it does actually not counter its purpose:
The frost pulsar is meant to push and keep an enemy at distance.
If frost applies, the enemy stops and will not come closer. If no frost applies, the enemy gets greatly knocked back.
=> So the frost pulsar is like 'get enemies at distance while beeing able to have more time to think what you do or defend another direction.
The very opposide is the Wildfire:
Since there is no status that lets an enemy stop midway, you can almost run unstopped through a wide place and create a tunnel across a wall of monsters while keeping pushing them away further and further.
The downside here is that you had difficulties to defend multiple directions at once since enemies come back faster after they got knocked away
=> So the Wildfire is about pushing enemies into the direction you walk creating tunnels.
The shock pulsar... well it is kinda a mix out of the previous 2, but since you mentioned you like voltedge, you may consider this pulsar, too.
------- Autoguns -------
When people talk about autoguns, they usually think about charging up and 1hitting trojans or killing Vanaduke with great speed.
The truth is: if you are new to autoguns, you have a hard time learning that you will not move while you shoot. Your Swiftstrike Buckler helps here, but this is still far from beeing safe. It is very easy to miss enough shots against a Trojan to make him turn around and make stawberyy jelly out of your face while you reload. I can not recommend the charge attack for beginners.
The normal attack however looks different: it is best used by only using the first 'hit', then wait a moment to prevent reloading after another hit, then use another time the 1st hit, etc. While doing this, make sure to keep distance to enemies. Devilities really fall for it as long as you do not reload and keep your range.
Side note: (Maybe auto-aim helps against missing trojans, but I switched autoaim like 3-4 years ago offline and never missed it as gun-prefering player.)
------- Antigua -------
I started with a blaster like everyone, but only antigua did teach me actually aiming at enemies.
You have the most shots per clip amongst all fully moveable guns by also beeing able to just rise your shield whenever danger is giving you the need to shield.
So this gun is great for 'practicing' aiming and missing 2 or 3 shots per enemy is less punishing than missing 2-3 shots with a master blaster.
=> Antiguas are best for practicing aiming for gun starters.
------- Tortoguns -------
Since you already know the mechanic with flourishes, you should be able to handle the normal 'shots' with easy, since it has the same knockbacking forward-dash pattern - well with an additional shard shooting out (though only 2 attacks before reloading).
The charge is planting a little safe zone inside the room that is leasting for a moment. A moment that should give you time to charge a sword between the safe shards and launch an attack out of your shardy castle.
This gun has some 1hitting trojan potential after one charge, but this requires very much skill. As a starter in these weapons I would just recommend you to see them as
-utility that creates ares that can monster only hardly pass
-and as 2-hit florish pattern guns with shadow or elemental damage.
Of course there are all 4 types of damage available in tortoguns, but I really can not suggest you to use yellow or red. Not yellow because devilities can just walk between the crystals and wolvers trigger their teleports with each normal attack - and not red because the red version is the only version that can not kill a small enemy with only 3 charge crystals landing on it (which is the usual to-be-expected case).
------- tldr -------
Pick the shadow-frost Pulsar and an Antigua type of your choice (recommending elemental though)

As in, the ones that have 6 shots before a reload, like most real life revolvers.
That being said, though, try using auto-aim until you get better at pointing your gun in the enemy's general direction. Blasters have big shots, so try hitting the center of where the enemy will be when you shoot.

Those are Antiguas, not revolvers.

If I wanted to say Blaster, I'd have said Blaster. If I wanted to say Autogun, I'd have said Autogun. I said revolver because the Antigua splits into three paths, and I wanted to use a generic name for the gun type since Antigua deals Pierce, so I classify it as part of the Gilded Griffin line for damage's sake. But enough arguing about it.
Anyways, back to the topic. All in all, I'd recommend a fast firing, quick reloading gun for all purposes with a decent reload speed and good mobility, so Blasters and revolvers are the way to go, with Alchemers and Pulsars as a maybe. From then on, it's just a matter of choosing which specific line you want if you're only going for one.
As a personal note, I'm Valiance for life.

Eh, just get a Polaris and annoy tryhards in lockdown

it works fine, if you cant get the savage tortofist to work thats an issue with your skill, not an issue with the gun

@Vohtarak:
I can play with the yellow, too, but the opening stated that the user is a beginner in guns. Thus it would be very annoying to be forced to deal with the cons I mentioned with almost your first gun. My recommendation went to the more user-friendly guns though these may not be the best choices in pure dps.

what I was saying was that the gun isnt bad, which you said it was, it doesnt have any cons with beasts or fiends, it just requires a slightly open mind and a very low capacity to figure out new strategies so it works, you can learn it in a day just like everything else
obviously a tortofist shouldnt be a recommended first gun, thats why I didnt say I was recommending it, a tortofist isnt a good choice because theyre from a difficult event thats once a year, and event weapons that require almost the whole crafting line to need a specific material thats around 1 week of a year is, of course, not optimal to a newer player who wouldnt be able to get the item during one event's timespan
Though I haven't played the game since before the Gunner update, I have only used guns since my first return to the game.
-A good, all-purpose gun would be the Valiance, as it deals Normal damage and it's main feature is the knockback and the stagger it can deal at pretty much any range, namely from the charge shot. Its rate of fire is pretty decent too, as is its mobility and reload speed. It'll get you out of any situation, but there are better options. It was my signature weapon way back when.
-Another gun that performs the same purposes as above would be the Normal Pulsar variant. However, you have to be at a certain range to get the full benefits. I'd prefer the Valiance in that case for its versatility. Also, you're better off getting the Shock variant because of it's effectiveness against the enemies weak against Elemental damage. If you're gonna specialize in keeping enemies at bay, might as well make sure it's with something they are probably weak against.
-Revolvers in general, whether they be Pierce, Elemental, or Shadow, offer great DPS for good mobility. The downsides are the charge and the lack of knockback (though not many guns have noticeable knockback to begin with). Another all-purpose favorite. 6 shots until a reload, but fire 5 shots and wait a split second and you'll have a full clip again whilst saving yourself some time. Just be sure to count your shots.
-Autoguns are good for groups of enemies or for turning nearby enemies into a pincushion. You're best off using the Blitz Needle variant for damage, unless you want more of a support role, which I'd recommend Plague Needle for its poison. Personally, I'd rather not use a Pepperbox because I can't shred Wolvers and Devilites with it as quick, but hey, don't let me dissuade you if you want a pseudo-flamethrower. As for the Shadow variant whose name eludes me, I'unno, seems good for Gremlins and Slimes, which tend to group up. Came out after my untimely computer break.
-HEY THERE, TOUGH GUY! DO YOU WANT A GUN THAT HITS LIKE A TRUCK WITH THE BULLET SPEED OF ONE TOO? Then get the Magnus! I got the Callahan for Piercing damage. It's good for the above mentioned Wolvers and Devilites, as well as Gremlins, because they dodge shots. Magnus shots shoot faster than they can react, and it's super effective against the former two enemies. It's saved my hide a few times better than my Blitz Needle could because of that. The Iron Slug does the same, but with Normal damage. Seems like a good all purpose, but I remember in my time people hated it. Nowadays, it seems more people are getting into it. I would've, but I'd rather office supplies not be thrown at me as much. Also, the animation for firing a charged shot for all Magnus-type guns is hilarious to me.
-Finally, you got the Alchemers. I fell in love with them, but I don't think they're for everyone as they're 2 shots until reload. Their main feature is their rebounding/splitting shots. Good for groups of enemies as well as bigger ones if you aim the charge shot just right. Nothing too fancy, but they tend to be situational. I have an Umbra Driver for Shadow and a Cryo Driver for Elemental, though I wish I had used the Nova Driver line instead since the Ice isn't too reliable on a gun.
-Ultimately, if you only had one gun, I'd say get the Normal-damage Valiance. I know there are other guns I didn't mention, namely a few more guns released with the Gunner update like the split Valiance paths, but the ones I've mentioned I feel are the most important to mention. And yes, I did take the time to look up those guns that came after I couldn't play any more. I hope that I could be of help.