PUBG: BATTLEGROUNDS

EDIT: There have been a LOT of changes to the meta of this game. Weapons being added, changed, etc.
I do not play this game anymore at this current time, therefore my recommended loadout might not be that great of an option anymore, or maybe it is. The rest of the solution should still be helpful to some though.

200 SMG, shotgun, or pistol kills.
Obviously Sub-Machine Guns are the go-to choice here, you can use any combination of weapons within these categories, it doesn't have to be 200 with one set weapon/weapon category.

My recommended loadout would be:
-A Longrange weapon, such as a Sniper, DMR, or an assault rifle with a 4x or 6x scope.
-A UMP or a Vector SMG.

Out of these 2, the UMP is definitely more versatile, but the Vector offers a faster Time-to-Kill potential. Try them out and see which one suits you better.

For both of these weapons as attachments I recommend:

- Compensator (SMG)
- Vertical Grip
- Extended Mag (SMG) or Extended-Quickdraw Mag (SMG)
- Red dot sight.

The Vector also has a 5th attachment slot for the Tactical Stock, this greatly improves the weapon.

Personally I just stuck with whichever one of these I found first, however choose what you prefer. I strongly recommend against using the Vector if you don't have an Extended Mag for it, as it'll only have 13 instead of 25 bullets in a magazine.

Considering the fact that finishing a knockdown, or killing the last player on a team are the only things that count towards the achievement progress, I'd recommend playing solo.

Drop in populated areas if you want a fast completion, or feel confident in your skill; Drop at quieter places if you're not too confident in your skill.

This achievement will come naturally as you play more matches. SMGs, Shotguns and Pistols are the most common weapons to find. A strategy you could use if you want to knock these out quickly is to do a "hot drop" which is jumping out of the plane as soon as you can or jumping into an area that is popular and many players go to. This turns into an arms race to find the nearest weapon which is normally one of the three mentioned above and then hunting/killing the nearest person before you start looting.

Here are all the weapons (with a few bits of info) that apply to this achievement:

SMGs
Micro Uzi - 9mm. Iron sights only. Damage = 26
UMP - 9mm. Accepts all SMG attachments. Damage = 39
Tommy Gun - 45ACP. Iron sights only. Extended mag gives you 50 rounds. Damage = 40
Vector - 45ACP. Only holds 13 rounds unless you get an extended mag. Damage = 34

Shotguns
S12K - Semi automatic shotgun. Takes AR attachments. Damage = 22
S1897 - Pump action shotgun. Can be modified with a choke and bullet loops. Damage = 24
S686 - Double barrel shotgun. Can be modified with a choke and bullet loops. Damage = 24
Sawed Off - Double barrelthat takes up the pistol slot and can only be found on Mirimar. Damage = 20

Pistols
P18C - 9mm. Firing mode can be switched to full auto. Damage = 23
P92 - 9mm. Damage = 35
P1911 - 45ACP. Damage = 41
R45 - 45ACP. Can only be found on Mirimar. Damage = 55
R1895 - 7.62mm. Slow fire and reload revolver that packs a punch. Damage = 55