Whenever you charge the gun to shot mulitple bullets then switch weapons, it will stay ready to shoot multiple bullets. So you could shoot 4 bullets at once rapidly.
Any of the charge swap gun exploits should get fixed or people using them get reported. Glitching items to get advantages over other people is pretty bad to do.
This has been reported quite a few times, however I don't think anyone that uses an eleos uses this
Not sure why it hasn't been fixed though
to be fair i stopped once i was asked, but this bug was reported since the day it came out, as far as ik the eleos and the lazarus havent been fixed and i mean who knows