I was playing on experimental official LA server. I fired my IJ70 with a single bullet in chamber, it got jammed so I held R to unjam it, I released R when I saw on the bottom left corner it said 0 instead X it finished the unjamming animation by itself. Next time I hold R it doesn't do anything, no reloading etc, gun is still badly damaged and nothing is in chamber. I have ammo in my inventory for it. Firing or emptying chamber doesn't fix the problem. Manually dragging ammo to the gun in inventory does show the orange compatible but also doesn't do anything. It is glitched for whatever reason.
Edit: Left the server and the game then came back, now it looked like there was casing in the chamber but still R wouldn't do anything, dropped the gun on the ground, picked it up then it let me empty the chamber. I tried to reproduce it but it didn't happen the next few times gun jammed.