This mod aims to allow chaining melee charges right after the melee attack was executed for all melee weapons, to avoid awkward switches back to firearm in between. By holding melee button right after performing a melee strike you should be able to start charging a new melee attack right away instead of having to see your firearm get half raised and then lowered back. The video should explain it better:

List of affected weapons:

Known issues:

• "Ghosting": Some melee weapons briefly appear in the middle of the screen during the transition between the melee strike and charge. I'm not sure if this is possible to avoid with the current animations.
  
• Wing Butterfly Knife and Chain Whip still have a very brief change back to the firearm between the attack and the charge (noticeable by the sound of weapon switching and sometimes ghost of the firearm at the bottom of the screen), but without it their charging animation breaks.
  

Installation:

• Download and install BLT.
  
• Unzip the archive with the mod into \Steam\steamapps\common\PAYDAY 2\mods