1) download the weaponv4 table from its thread (page 10 i think)
2) open cheat engine, load the table, select process
3) set every primary-weapon-value to 179500 and the secondary-weapon-value to 12000
4) get 1 kill with every primary weapon and 1-10 kills with your secondary! (secondary lvl 10 xp are different)
5) why not 179601? Because you get extra xp for reaching weaponlvl 31 and a nice title ^^ also on secondaries
6) u can use double xp too if you want i don't think i have to explain why...