They are unlocked as you rank up but you have to buy them.
Play 9 Boards And Unlock 9000000 Guns!
Unlock By Leveling Up, And Purchasing With COD Points
3575
you have to get to the higher ranks befor you unlock the better guns but some people like the guns that you get at lower levels
After you unlock all the guns from one class of guns like LMG's then you get a classified weapon.
You unlock guns by reaching the level required to unlock that gun, but if you want to use it in your custom class, you have to buy it using COD points.
while doing the glitch you unlock all the pro perks and guns no matter what level you are.
On Xbox live you beat all the levels then go to prestige
You need to unlock every gun in a single category that has a special weapon in it for it to be available to purchase.
you would give yourself a pat on the back and you could mabye unlock new maps,levels,and guns
In Black Ops multiplayer you unlock the AK-47 at level 38.
in black ops multiplayer, everything's unlocked already.