(adsbygoogle = window.adsbygoogle || []).push({}); Credit to: Niall47 for allowing me to share his method

Here is what you need:

• Primary weapon where you are close to earning a 10,000 XP bonus (500 kills, 250 headshots etc)
  
• Secondary weapon (Only tested on pistols so far)
  
• Slight of Hand Pro (May not be neccassary)
  

What you need to do is to get the kill with your primary weapon and immediatly switch to your sidearm, before the 10,000 XP comes up on the screen.
If you do it fast enough the XP will be added onto your secondary also. On a pistol with 0 kills I managed to get just shy of weapon level 9 by doing this glitch once. The video below I was only level 2 with my .44 magnum and the XP maxed it to level 10 and gave me a further 10,000 XP for doing so.

Here's a video of it in action:



For the trolls or misunderstanding people of the forums...

idc if all these people say this is old i never knew about this and its a pain leveling my sidearms up v.v thank you <3

still works just did this on my Deagle

Old!!!!!!!!!!!

doesnt work with pp90m1 so i thought it would be same with all smg's but it worked with ump, it was a nice 30,000xp coz i acheived all with the ump also very nice thanks man

worked perfectly!!