As you all know. (or most of you :P) team fortress 2 has been updated therefore fixing the achievement weapon unlock.
BUT! my good man/woman, tis not true! for you that don't know or do know, they tricked us! seeing as how I unlocked the "Ambassador" after unlocking the "spy milestone 1" I found the pattern.
1. Go get an achievement map.
2. Get/play tf2.
3. Choose a class and play the map.
4. Put: sv_Cheats 1 mp_teams_unbalance_limit 30 bot -team (team colour here) -class (class here) in the console.
So you have a bot now... now I know you're thinking at this point Oh boy I am gonna get a weapon! But no.
THEN you put sv_cheats 0 in the console.
Then you put in: retry
Then you will find you're bots in the same place you left them. By now the game has been tricked into thinking the bots are players. Then find some achievements you want to do and do them.
(The bots will respawn just like players.) NOTE: You CAN use this for every achievement, HOWEVER! it can be REALLY hart to get it just right. EX: I was trying to get the "plan B" achievement for the pyro and it took FOREVER because the scout bot was hard to move. But I did. So....happy bot slayin!
And for those of you that know this. don't post. Thank you have a nice day. BOINK!