HELP myarms wont grow

Ive been training for about 5 months ive made freakish gains when i started i had trouble benching 135 for 10 reps now i can get 245 10 reps and if im feeling really saucey i can nail 255 relitivly easy and my one rep max is 315 my chest is growing crazy fast as well as my legs and back but my arms are frusterateing me  they are getting strong but not really getting any bigger  there more cut but not really growing any ive tryed just about everything i can think of  i just cant seem to get them to blow up the way the rest of my body is  any ideas???????  right now my arms are almost 17in  my typical arm routine starts with 4 sets of light dumbell curls to warm up  4 sets of barbell culs 8to10 reps and i cheat one or two in there the last 2 sets  and 4 sets of preacher curls or incline dumbell curls  i switch it up from time to time doing concentration curls and 21s in place of the preacher curls  i rest them for 4 days between workouts i put a lot of focus in my arm routine i lift slow with good form  they just wont grow

How's your diet?

it could be better  but i seem to have no trouble makeing good gains in other areas

No offense, bro, but that sounds like every guy on the planet.  I've been packing mass onto my quads and hams like crazy, hitting squat poundages that blow away anything I've ever tried before -hell, even my LATS are finally starting to respond to training; but my arms just sit there and laugh at me.  Of course, I track measurements with more scrutiny than most people would consider healthy, and I cannot, in good conscience, claim that my arms are not growing.  Not growing as fast as I'd like?  That's a whole different story.

Is it possible you're over-training them?  I can't imagine how 21's could possibly be any good for a muscle group as small as the biceps.  I just don't think it's the kind of muscle that will respond to "more".  Every time I read somebody's advice about getting the arms out of a slump, it always comes down to the same tune:

Stop hitting your biceps directly.  No more concentration curls.  No more tricep isolation moves.  NADA.

Instead, hit standard & narrow-grip chin-ups, and Upright & T-Bar rows for your back.  Stick with barbell bench presses and dips for your chest, and military presses for your delts.  The biceps and triceps, they say, get all the stimulous they will ever need in the process, and the bigger, compound lifts stimulate more testosterone production.  If it's true what they say -that every inch on your arms requires approx 15 Lb of total lean mass gained- then clearly, the emphasis should be on gaining mass everywhere else, like you say is happening.

I'd be interested to know if you've tried this, because I cannot say objectively that I've ever had the patience to take my mind off my direct bicep/tricep work long enough to notice if it works.

Yes, that's me in my avatar, and NO, I don't look like that today. That was taken back in Jan '07, and I lost most of that progress when I slacked off last year. I'm on my way back, tho, and I'm using that photo for inspiration.

Bgjay:
 
Pretty much what vegeep said, sometimes there is no need for direct arm work when doing heavy compounds. I for myself didn't do any direct tricep work or bicep curls and i've manage to develop both from bench, military press, deadlifts, bent over rows and chin ups.

wow i cant imagine not isolating my biceps thats like my favrite part to train  i measured them lastnight after posting this and it would seem im makeing a lil progress mabe a half inch bringing me up to a solid 17in   i will just have to be paitent   thanks

ORIGINAL: BgJay

wow i cant imagine not isolating my biceps thats like my favrite part to train  i measured them lastnight after posting this and it would seem im makeing a lil progress mabe a half inch bringing me up to a solid 17in   i will just have to be paitent   thanks

If you enjoy your bicep training, you're not doing it right.

If I were you, I'd just take a rest from training them.  Let your biceps get lazy and content by not be isolated then shock them back to growth.     

No, I'm not on steroids but thank you for asking.