The Water Pistol: A serious guide about a "joke" weapon

WARNING: The final tidbits in the "What can it do exactly?" section has slight spoilers, I will put another warning there if you wish to still read this guide.

The Water Pistol is a gun that seemingly has no use at first glance other than to be a "joke" weapon, much like the Banana in Peace Walker which also had the small bit of usefulness of being able to hold people up, but this isn't just the case in Metal Gear Solid V: The Phantom Pain.

You can develop the Water Pistol after completing Mission 18 and obtaining the key item for doing so, after which you just need a sufficient R&D level and GMP to complete it. The Water Pistol can also be upgraded with fairly high level R&D (the final upgrade requiring level 52 R&D) with each upgrade giving it a higher effective range stat.

Now on to the main part of the guide, just what uses does the Water Pistol actually have?

Like most weapons in the game, you can hold up enemy soldiers using the Water Pistol, meaning it doesn't lose the ability of incapacitating enemies in that regard.
Similar to Tranquilizer weapons, if you shoot near a guard, they will hear the impact of it hitting the ground and go to investigate it without getting alerted. They do not consider this to be an attack, so it has the same effect as the Magazine does of being a source of infinite ranged noise making.
When shooting at fire sources such as torches and firepits, you can extinguish them and make it that much more darker for when you need it. Brought up in comments by Wild Salmon

Considering the Magazine is not able to blow up mines, that leaves the Water Pistol to be the only infinite source that can blow up a mine from a distance (outside of maybe the Rocket Punch). Generally it is better to just go around them and pick them up, but still has a use of being ranged mine disposal.
Now into some of the more potent and technical usage of the Water Pistol, if you get a direct shot to the face of an enemy, they will recoil and be blinded as if they've been flashbanged. This stun lasts for roughly 3 or 4 seconds and does stop an alert if you're quick enough. This can be easier said than done since the fairly short effective range early on makes it tough to get a direct shot outside of pretty close range, but it has saved me on more than one occasion when CQC would have been too slow.

*Special testing for the bug related to this*
Brought up by PoyoSamaLlamadingdong and Domesticon

I mostly did this to see if there were any beneficial effects to the bug that occurs when you shoot an enemy in the head/face to blind them while they're otherwise incapacitated in some way. Here's the basic findings from what I could tell:

• You cannot grab someone in this position regardless of status effect
  
• Actions are delayed while they are in this effect, due to them still being considered on the ground but doing another animation
  
• However for some reason, their hitbox is still equal to their actual model, meaning all contextual actions have them considered on the ground, while they are considered to be standing otherwise
  
• Guards seem to face the direction they were shot from when doing this
  
• Oddly enough, each of the status effects retain their "effect" while in this position except for stun, which turns into triple dashes.

So in short nothing really fruitful outside of maybe the direction thing, maybe needs further testing or other bugs that might be possible with it.
Last but definitely not least, is the VERY useful ability to take out electronics silently without the use of explosives. All it takes is one shot before the target starts fizzling and eventually gets destroyed all with much less suspicion than the normally used explosives. This works on Communications Equipment (The small Satellite Dish looking equipment), Radio Transmitters, and the Power Supply giving a very quick and silent way of crippling the enemy. Just make sure you hit roughly where the blue light is or where you can see the vents on the machine when it comes to the Communications Equipment.

FINAL WARNING: These are the slight spoilers I was talking about at the very beginning of the guide, so stop here if you don't want ANYTHING spoiled at all.

Brought up in the comments by Steiner

Despite my original testing, you CAN extinguish the Man on Fire with the Water Pistol, but it takes roughly 3-5 full magazines to do so. Outside of that, you can also stun/stop him from doing some of his attacks by hitting him with it if you decide to do that but from what I experienced he just generally rushes you after that. Brought up in the comments by cant wake up.png and Cipher " David " Zero

In the fights against the male Skulls, you can use the Water Pistol to cause them to be stunned for roughly a second as they absorb the water, you can actually use this to stun lock them if you time the shots right. As for the female Skulls, the Water Pistol does have an effect on them, but it just acts like they took a shot and relocates like normal. *Retest* - The Female Skulls can get the same stunned effect as well, but you have to be extremely close to them for it to work and still causes them to relocate, so it's of little usefulness.

Okay, so how does it compare to other choices in your Pistol slot. Here are the general pros and cons compared to the generalized choices.

+ On average is much cheaper GMP wise, with the Wu Pistol being the same price only at level 1 and getting much more expensive as it becomes more developed
+ The advantage of being always silent, until Wu Pistol gets the built in surpressor, but is still a huge cost gap
+ Has infinite ammo
+ Can take out most electronics and fires silently in one shot
+ Can stun enemies when shot directly in the face
= Can make noise when shot near enemies without alerting them
= Can perform hold ups
- Cannot put targets to sleep
- Doesn't have as much in-combat potential, which is saying something when compared to the Wu Pistol
- Much less range in which it's useful in
- No customization
+ All the same pluses as the Wu Pistol comparison
+ Since it's a non-lethal weapon, it can help stop alerts without killing or injury
+ Doesn't count as an attack when shot near enemies
= Can perform hold ups
- Much less combat effectiveness
- Much less range in which it's useful in
- No customization
- Less flexible Generally the exact same as Lethal Pistols/SMGs but with the obvious change of being able to stop alerts without injury or killing.

Hopefully this guide has shown that this seemingly joke weapon is actually fairly potent when used in the right way. Seeing as it's only one slot in your loadout, you can easily make up for its shortcomings in all of the other slots (Sniper rifles can tranquilize and be silenced, Shotguns and ARs can stun, Bionic Arm can even help with long range stuns, and the obvious lethal choices if you want something like that in your loadout).