Yepp, especially the MOLLE gear is worth it's weight in gold, since it DOUBLES ammo carrying capacity, great if you run something like the Laz Sniper ^^

Yeah, i bought a lot more, still some left tho, guess that is the "issue" hope there will be more content with some artifacts around (or just an artifact vault i missed xD), i am a bit of a collector ^^

Fusion Cannon
This is a heavy automatic fusion gun with an overheat mechanic and no secondary attack option.
Find BM 061 through the hidden entrance behind warehouse 27 in Junction 06. Follow the hallways in BM 061 until you reach the room where you're attacked by constantly spawning phantoms. Turn around and climb up one of the ladders on the wall. Then balance along the steel girders across the room to reach a boarded-up door. Destroy the wooden boards to find a red chest (and lots of other goodies). The red chest should have the Fusion Cannon. Note: I found the Fusion Cannon the first time I found the red chest. When I exited the area and entered again (still carrying my Fusion Cannon), the red chest had some other weapon in it. But when I returned later, after I had discarded my Fusion Cannen, it respawned in the red chest. So either this chest just has a good chance of spawning high-level weapons or it spawns the Fusion Cannon only if you don't already carry one.

Pulse Rifle
This is a burst-fire rifle which seems to fire a variable number of bullets per burst.
Enter the Stag Bunker in The Pines. After swimming and diving, you will eventually come upon a boarded-up door. Break the boards to enter another hallway. Enter the door opposited the (previously) boarded-up door to find the Pulse Rifle to the left, opposite the data reader machine.

This one isn't in a fixed location and it doesn't respawn, but I figured I should mention it here:
Concussion Rifle
This is a gun that causes near-instantaneous explosions at the point of impact. If you've played Dark Forces or Jedi Knight, you know what this gun is all about.
After doing the quest for the Free Scrappers where you have to find one of their scouts, another person in the Free Scrapper camp will give you a mission to kill three Conflux Cardinals across the zone. These three Cardinals carry Concussion Rifles, but once you kill them, I don't think they respawn, so you won't be able to get more Concussion Rifles.

I am pretty sure that the Concussion Rifle (just like the Scorcher for that matter) have a chance to spawn in weapon boxes you sometimes come across (for example there are two in a boarded up tunnel in the catacomb mines, just next to the "shielded computer box")

I destinctly remember that i found one randomly in the cathedral and had a great time shooting enemies off the bridges there ^^

EDIT: now that i think about it some might only spawn in the much rarer red ones like the one you mentioned, might be worth to track them all down and catalogue them ...

Pretty sure the Scorcher CAN spawn in the long green ones though.

EDIT 2:

And btw the Pulse Rifle is far from a unique weapon, you can buy it from Red Rook, it also rarely spawns in the aforementioned red boxes ^^, also it fires in an interruptable 8-9 round burst

EDIT 3:

But thank you for making me go back into that bunker, behind the boarded up flooded stairway in the second flooded room: the ceiling has a massive hole and you can get one of the red weapon crates from down there with your gravity arm, it's only guarded by a watchful mannequin (provided you came here after the mission ^^)

Like I said earlier, these guns may not exactly be unique, as I erroneously suggested in the thread title, but I'd say they are pretty rare in the wild. And the spawn positions we're collecting here are supposed to be "guaranteed" or "very likely" spawn positions to make it easier to get these rare weapons.

For example, I know that you can buy the Pulse Rifle at Rook's (much like the Phantom Rifle I've mentioned before) but since artifacts are finite (aren't they?), I think it makes sense to mention good locations to find them without having to pay for them.

Also, I've seen lots of Scorchers so far, but not a single Concussion Rifle. Maybe that's just my luck. Or maybe they only spawn in the Cathedral? Can you give me a pointer as to how to get there? I've been to the Power Plant and the bit with the "big giant head", but I don't recall a place called the Cathedral. Maybe I should go back there and keep looking :D
EDIT: Nevermind, according to the most recent patch notes, the Cathedral has been renamed to Power Plant "to avoid confusion" ;)

Alright that makes perfect sense! Mmmmh, maybe "Secret Weapons" then? Well, anyway, i keep my eyes open ^^

Might start a seperate thread with weapon crates locations soon, especially the red ones seem pretty damn rare but even the green ones seem to spawn some rare weapons like the concussion rifle relatively often.

Good idea with the crate thread. Given the sheer amount of different codes, rare weapons/crates, upgrades like armor and goggles etc. in this game, I think Adaca is kinda begging for someone to make a proper guide at some point, anyways.

One thing to note: Some of these actually spawn in the respective campaign missions as well, such as the crossbow. I do have to say though, it would feel a lot more useful if the arrows didn't penetrate enemies and instead stuck into their bodies. Trying to find overpenetrated arrows again can be a pain in the neck.

in the dish, if you start from the free scrapper base, from the second floor of the building there you can jump to some pipes and run along them past 2 water tower looking things to what i think is an oil tank, if you jump you can use the gravity arm to grab a rocket rifle off the top of it, but its not a normal rocket rifle, despite not having a unique name or skin it has a MUCH larger blast radius as well as 69 (THATS THE FUNNY NUMBER LMAOI) ammo in reserve, might also do more damage, i dont know, but i did kill myself with it a lot. its also there in the campaign mission on the same map

引用自 Xlis1：

in the dish, if you start from the free scrapper base, from the second floor of the building there you can jump to some pipes and run along them past 2 water tower looking things to what i think is an oil tank, if you jump you can use the gravity arm to grab a rocket rifle off the top of it, but its not a normal rocket rifle, despite not having a unique name or skin it has a MUCH larger blast radius as well as 69 (THATS THE FUNNY NUMBER LMAOI) ammo in reserve, might also do more damage, i dont know, but i did kill myself with it a lot. its also there in the campaign mission on the same map

Very nice find! The game definitely treats this as a separate weapon from the normal Rocket Rifle (which means you can have both in your inventory), but the only way to visually distinguish them is the colour scheme: The special Rocket Rifle has orange (or reddish) highlights (not yellow/yellowish orange) and a teal ammo counter (not green). Also, with the Ammo Bags upgrade, you can carry a whopping 6+138 rockets with you, compared to the 6+36 rockets of the normal Rocket Rifle.

Oh yeah, minor thing but maybe interesting to some:

The Custodian Bunker in Storm Drain contains a well stocked armory, most of the stuff there is quite common: Carbines, Heavy Pistols, Tactical Pistols but among all these common weapons is a single Laz Mag, arguably the best sidearm you can get your hands and quite expensive to buy if i remember correctly and only rarely spawns in the rare weapon crates.

This should become a Guide rather than a buried Discussion.
Hmm... maybe I will just transfer it myself...

At the request of a few in the favourite weapons thread: The Ancient Rifle can (as far as I know) only be obtained by waiting for Mike to have it upon entering a new area, since he gets a new random weapon every time you load in. Once he's carrying it (It's a wooden bolt action rifle, looks like a Kar98k to me, but I could be wrong) pick up any weapon that's lying around, toss it to him with right click, and he'll drop it to use the weapon you tossed him instead. Then you can get your grubby mitts on it, and blast away to your heart's content!

Thank you very much ^^

And very interesting, if that rifle is the only "secret/unique" weapon that spawns on Mike i would go so far and say he is the only source ... but considering that i never really hung out with the guy and i didn't even know up until yesterday that that behavior is a thing i might have to run some tests first to make that hypothesis ^^

EDIT: And what's the first thing that happens then i boot up the game? Mike's running around with a Bum Leg xD