After seeing some videos about why US ammo was "meta" due to the -30 recoil modifier, and even after making a video about it myself, I've done some testing, and no longer think it is worth using.
I'm gonna break down my thoughts in this post, but I have a video form of this discussion at the bottom of the post, which also shows the in-game recoil difference.
Comparing BP to PS & US ammo.
BP ammo has 58 damage and 47 pen. PS has 57 damage and 35 pen, and finally US ammo has 56 damage and 29 pen.
Overall, the clear winner by raw stats is BP, with PS coming in second, and US ammo last, so why would anyone be using US ammo? Well, if you didn't know it has a recoil modifier of -30, which some have claimed to make spraying at individuals much easier.
Availability.
BP ammo is able to be crafted at workbench level three for 2 green & blue gunpowders. Alternatively, you can buy it from Prapor after completing the Grenadier task. Overall, while it's not the most accessible round, it isn't incredibly hard to come by. I for example have almost 4,000 rounds from just crafting it over the past few weeks.
PS ammo is dirt cheap and available at level 1 Prapor, with unlimited rounds available.
US ammo is also pretty cheap, but from what I remember, you can only buy 400 rounds of it, and it is only available at level 3+ Prapor
Use case.
When it comes to using US ammo, some people would suggest putting it in a meta gun build to allow you to "easily spray" down enemies. In my experience, this doesn't really work well in most cases, and leads me into my next point:
Armor pen
Sadly, whether we like it or not, most players are using level 4 and above gear right now. US ammo, with it's 29 pen just isn't going to cut it. Sure you can get more shots on target, but in my opinion, the 47 pen that BP provides is significantly more valuable than the lower recoil US gives out.
BP ammo is going to successfully take out a level 5 armor in 2-3 shots, and level 6 won't be far behind, whereas US is going to struggle hard to make it through even level 4.
Final thoughts
I'm not making this post to say "YOU SHOULD NEVER EVER USE THIS ROUND" however if you do like to have some reasons to run one ammo or another, hopefully this post will guide you to having more success in your raids.
Thanks for reading, I hope this was helpful.
THIS LINK IS A VIDEO FORM OF THIS POST, AND IS PROBABLY MORE CLEAR THAN MY WRITING:
^^^^^^