JOIN CT TEAM! 

settings: 
mp_do_warmup_period 0 
mp_freezetime 0 
mp_startmoney 10000 
bot_quota 10 
mp_limitteams 0 
//order is not important, but "mp_limitteams 0" better to be the last to type in! 

Classic Casual game mode is recommended. 
Each round you can get about 20-50 !!! KILLs (depending on weapon). 
For getting the 10.000 kills, use negev, you can even get 80 KILLs! 

Buy the weapon which you want to earn kill achievement with. 
If you can't buy a T weapon in CT, type in console "sv_cheats 1" then "give weapon_galilar" for example if you want galil (replace with the name of the gun). 
BOTs are SPAWNING RAPIDLY, but just for the 20 second spawn time. /if you can tell me how to extend, please do/ 
I made this map because I couldn't find any useful on this purpose, I hope it will help you :) 

Map by Balzs