This is a ‘fairly’ big change regarding weapon mods and stack sizes in regards to what happens when adding mods to your weapons.
In the past: If players tried to drop a large stack of say 10k laser sights on their weapon, the server would have to process all 10k sights. It would allow 1 to go on the weapon and return the other 9,999 to the player’s inventory. As you can imagine with 500k stack sizes, this can consume a LOT of server resources which can cause lag for both you as well as other players. This is one of the reasons we have not increased stack sizes more.
To help with the server resources: Starting with the September 25th 5am reboot, the server will no longer ‘protect’ the stacks in this way. Players that drop a 10k or even 500k stack of mods onto a weapon will see the entire stack added to the weapon. Players should consider only dropping 1 mod from a stack onto their weapons (Right-click Drag and Drop) to prevent losing the stack if they lose their weapon.
Removing protections like this is not a choice we make easily. Players losing an entire stack of mods when they lose their weapon isn’t fun and we get that. However, we feel that it’s in the best interest of the server as a whole. Nobody likes any kind of lag, so we will always try to battle it as best we can.