It doesn’t, despite Plundra showing like so.
At least it didn’t for me. When i pulled my weapon out, all the attachements it had were still equipped to it.
What Plundra does show, errenously, is every attachement separately, even if they are equipped to the weapon. At the same time, Plundra shows no attachements on the weapon, even if it has them.
Can only equip #1 slot, #2 and 3 show as equipped but are not…
Pushing those numbers does nothing, and dropping everything and re-equipping doesn’t help. 
Edit/
Storing loot in Plundra and then re-equipping it worked for me!
I can’t equip Experimental AG 4. Rest of the guns is fine.
I cant equip Sjöqvist semi-auto, so far only weapon i have noticed. Doesnt equip on primary or secondary weapon slot.
Found other workaround
Emptying weapon slot, drop weapon and pick up, it goes to weapon slot.
The old 240 5.56 and 7.62 ammo stacks are still ‘in’ the old weapons.
It’s seems to be enough to remove the ‘old’ ammo stack to be able to re-equip weapon and tie it to new ammo.
Less crashes that way, but still I didn’t lose any weapons due to the crashing from the juggling of the weapons.
It’s almost not a bug, as the old system counted the weapon+attachments+ammo as a unit more or less, now it have to re-style the way the ‘unit’ works. (try dropping some ammo that isn’t even compatible with any equipped or carried weapon, and the equipped weapons more or less gets reset to standard vision mode, and currently used weapons gets lowered as if you just changed weapons.
But at the same time weapons in the lootbox and their attachments are tied together, but the attachments don’t show that they are tied to a weapon, so that can lead to tossing away/trading/recycling something that looked like it were a spare
We need to be able to ‘lock’ weapons, as it is right now it’s almost an invitation to accidentally recycle favorite experimental weapon, or take apart something in the box.
Hey all 
A high priority ticket has been created for handling this issue.
In the meantime, those of you affected can hopefully make use of one of the following workarounds:
Sorry for the inconvenience and thanks for reporting! 
Sounds like a similar problem that popped up awhile back where an equipped weapon couldn’t be loaded or reloaded with ammo, if you dropped said weapon then picked it back up it started working again. Wonder if it’s related, though I believe they patched that problem a few updates back.
its hard to say if its related , but the good news is that a dev has stated that it is a high priority for fixing .
ah i was having this issue earlier couldn’t swap them, thank you, hopefully they’ll have a hot fix for this out soon as well as the sights/scopes not showing what rarity they are, those are really my only complaints about the update
Hello. I have the same issue. But since I didnt see anyone saying what plattform, I just want to add that im on the PS4.
Noticed today that using the keybind E is much more reliable. If you use mouse to click ammo type, it like game shows it and it wont work.
Not sure if this can be replicated just by switching ammo around, but surely fix the equip problem.
Since the new March update dropped I cannot use some of my weapons. I play on Xbox One. When I assign them to a slot, i still cannot use them! The weapons that I can equip is the Kpist and the KVM59 (really nice experimental, good job Devs), I can also use my Magnus sidearm. Althogh I cannot use the Grg m/49, the AG5, the Sjöqvist or the PVG90. I really like these weapons and not beeing able to use them sucks. Since i can only use three main weapons I easily run out of that particular ammo. Please fix this asap. Thanks devs for making such an amazing game! Is anyone else experiencing this and if - which weapons and console or PC. I really hope this is getting fixed.
/sirjamesafkize
Another bug since the new update is that the game started crashing again. It has only happened once for me but I think others are having the same problem.
Have you bravely tried any of the ~3 workarounds that should’ve popped up for you when typing the bug/problem? 
Try to put them in the storage box (Plundra) and take them out again. (safest but unverified by me, as it sounded like a boring solution)
Remove the old ammo stack that is ‘stuck’ in it, visible with the old ammo stack size attached (verified by me, but can crash, no loss of weapons/items/chars on PC)
Drop the weapons one by one and carsfully pick up their parts and put them back together, ammo last! (verified by me and crashed like h*ll a few times, but no loss of weapons/items/chars on PC)
(4. wait for a hopeful hotfix along with the fix for crafting, and hope the rivals rust fast and drop event weapons)
Happy hunting!
I tried dropping the weapons and then pick them up again, and it worked!
Thanks! By the way, have you gotten the new experimental machine gun!
Yes thank you very much, i noticed this when i first launched the game after the update.
Then i tried to drop everything and pick it up again, and it worked.
But its tiresome to have to figure out new ways to play a game that has worked flawlessly before.
Threads merged.
/Mod
Yep I can´t use any weapon except the handgun.
I’ve tried to equip a new weapon but it takes me several tries then it equips but by that time I exit the menu I’m downed.
Platform: PC
Description: When loading character 1 i can equip my d-pad items but not my firearms, they appear to remain holstered. this issue only happens with my 1st character. Characters 2 & 3 i have no issues with.
Host or Client: Host
Players in your game: Playing by myself.
Specifications: Intel i7-6700, 16GB DDR4 PC4-2400C15 3000MHz, Asus Maximus VIII Gene Intel Z170, Asus Nvidia GTX 1070 Strix OC 8Gb, OS Win 10 Pro Version 1909 Build 18363.752
