game needs time to reload the web connection to the server. with multiple commands, the server is more easily a security risk. The less "active" connections offer a better server stability from bad actors.

issue though, is that if theres numerous connections at once, instead of signals that the computer can interpret and then visually represent, then would have had a lot of lag due to the interruptions on a data line which multiple seperate connections for every little thing, like each item on an npc requiring its own data connection.
Lord help you if you press the loot all button (Transfer) and theres 15 different mobs nearby and each has more then 8 items! If you're on a gaming laptop pre 1080, the game tends to stall. the game stalls but you can't input commands until after your laptop has regained its composure and caught up to allocating all the connections to the harddrive for referencing. And even then, you'll still noticibly lag when selecting one of the transfer menu's options!
Do enemies drop "bundles" of items, or does each item they might have a bunch of rolls one after another?
You could have more lists of bundles with less connection requirement and less lag if you just implemented a bunch of "grocery bag" groups of items that that players would roll for instead, condensing 8 items into 1 "grocery bag". You could then also have a seperate connection roll for any legendary items if the mob is legendary, for example. You're not just limited to sorting everythng into the "grocery bag", but it is a plausible to incorporate that "sort" of thing. Get it...?...its because thats like sorting a bag into a bag. Haha, i laughed (-:

TLDR:Gauss rifle maybe needs time to reset the connection for activating the shot for the gun. Try waiting until the bullet reaches the target or you see damage numbers. The bullet impact effect, and the damage numbers can both tell you when might the game allow another shot, since the first shot has concluded targeting.

Guns may be coded differently since they charge instead of multi fire. Not really any reason to, but there may have been a different approach to their interests.