This Subclass is an adaptation of and heavily paraphrased from Pointy Hat's Ranger Subclass "The Cowboy", check them out on youtube.

"The prairie grows quiet as the sun sets below the dry grass and gentle hills in the distance. A rustling of the bushes, the gentle breeze, an occasional stomp of hoofs. The night sets in under an endless sky. The light strum of a guitar fills the cooling air. This is where you belong."

"'Alone out here?', a nod. 'Why, mind some company while we wait out that storm? Getting mighty dangerous out there.", another nod, a grunt, they point next to their fire. 'Well isn't that somehtin' out here? By the looks of it you must be knowin' those plains like the back of yer hand - a ranger I presume?', they look up and you can see just for a second the flicker of untold tales and adventure in their eyes. Another nod."

"When out there you must be careful, only them rangers with their tricks and grit be survivin' out there on their own. Some say they in league with them devils and spirits roaming the plains. Others say they are the land itself manifest to help out lone wanderers. I for one don't care if they're devils, ghosts or whatnot. All I can tell ya is, if you alone at night and all you have is yourself and the darkness pressin' on ya, look out for their campfires."

As said above, this is a modification of Pointyhat's "The Cowboy" subclass for the ranger. While I liked the base concept and only expanded upon it, I wanted to inject some more magic for the later levels and also make it a bit more powerful along the way.

Arcane Cowboys are centred around firearm combat, so align with your DM if they are permitted in their game and what ruleset you will be using for those. Apart from that the Arcane Cowboy weaves in some magic into their bullets making them stronger half-casters in the later levels and allowing you to utilise your spellslots a bit more freely.
They can also befriend beasts, defusing a dangerous encounter on a clearing, making friends with the local fauna or even acquiring a trusted life-long partner over the campaign. Speak with your DM on how these interactions will be handled and let them know what kind of cowboy archetype you want to play so they can plan accordingly.

Cowboy Magic

3rd-level Arcane Cowboy feature

You learn an additional spell when you reach certain levels in this class, as shown in the Arcane Cowboy Spells table. Each spell counts as a ranger spell for you, but it doesn’t count against the number of ranger spells you know.

Cowboy Spells

Ranger Level	Spells
3rd	Animal Friendship, Longstrider
5th	Find Steed, Heat Metal, Rope Trick
9th	Haste, Phantom Steed
13th	Dominate Beast, Faithful Hound
17th	Awaken, Hold Monster

Cowboy Marksmanship

3rd-level Cowboy feature

When you choose this archetype at 3rd level, you gain proficiency with firearms. Additionally, you also gain proficiency with tinker’s tools, allowing you to craft ammo for any firearm for half the price it costs to buy it. Crafting a set of 10 rounds of ammo takes 1 hour.

Beast Whisperer

3rd-level Cowboy feature

Also at 3rd level, your expertise and know how of dealing with animals allows you create a supernatural bond with any beast. As an action, you can attempt to befriend a beast that can see and hear you and is within 30 feet of you. You must make a Wisdom (Animal Handling) check. The DC for this check equals the 10 + CR of the beast, rounding up. If the check is successful, the beast is friendly to you, trusts you, and will heed some of your commands within reason. If the beast is hostile to you or your allies you have disadvantage on the check and the creature will stop fighting you on a success but is not necessarily friendly afterwards (up to the DM's discretion). Also if you fail the check, the creature is immune to the effect for the next 24h.

The beast won’t attack your enemies and it won’t engage in any action that will lead to its certain death. The beast will, among other things, bring you an object out of your reach, carry a message to someone it could reasonably find, indicate the way of a location it knows, scout ahead, or, if its biology permits it, carry you and be used as a mount. If you choose to do so, it gains +10 feet to its speed when you mount it. Willingly harming the beast will make it stop seeing you as a friend, at which point it might turn hostile depending on the nature of the beast in question, at the GM’s discretion. The beast will not leave the general location where it lives for more than 100 feet, as in, befriending an elk that lives in a particular forest means the elk won’t follow you anymore once you are 100 feet away from the forest it lives in.

Hot Hand

7th-level Cowboy feature

At 7th level, your expertise over firearms grows, making you an even more prodigious marksman. You can reload a firearm as a bonus action instead of an action, and the range of all firearms is doubled for you.

Magical Bull's Eye

11th-level Cowboy feature

At 11th level, you gain the ability to infuse your bullets with your own magic, allowing you to perform a shot so precise it supernaturally tracks its target. As a bonus action, you can spend one of your spell slots to empower the next ranged weapon attack you make with a firearm. When you do so, this attack gains a bonus to its attack roll and damage modifier equal to the level of the spell slot used, ignores any bonuses from cover, and is not made at disadvantage when firing at long range or against an enemy within 5 feet of you.

Also when you craft new ammunition you can now create magic infused bullets.
Using an hour of intense labor and materials costing 10GP per bullet you can create an amount of magical ammunition equal to your spellcasting modifier+profiency bonus. You can use this feature once per long rest.

Using these bullets requires loading them into the barrel/magazine, effectively requiring you to reload your gun (features or feats, that apply to the loading property apply to this as well).

Bullet-types you can create:
Volatile. When this bullet hits a surface it causes an arcane detonation dealing 1d6 radiant and, if they fail a DEX Saving throw against your Spell Save DC, 1d6 fire damage to all creatures within 5ft. of its target.
Walloping. This ammunition packs a wallop. A creature hit by the arrow must succeed on a Strength saving throw against your Spell Save DC or be knocked prone.
Bounty. On a hit, apply the effects of Hunters Mark to the target. This lasts until the target creature drops to 0 hit points or, using an action, removes the bullet from its body, or the magic gets dispelled by another effect.

Arcane Quick Draw

15th-level Cowboy feature

At 15th level, spellcasting and shooting have become so natural to you that you are able to weave your spells into your bullets. When you make a ranged weapon attack using a firearm against one creature, you can cast a spell that targets the same creature or object the weapon attack targeted as part of the same action - this includes area of effect spells, making the target the point of origin for this spell (spellcasting rules apply). You can use this feature a number of times equal to your wisdom modifier. You regain all uses of this ability after finishing a long rest.