bro:
for safe AR, i would say try to get as close as possible to 400-450 (500 with perfectionist)
for intelligent stone, you only gain 5.8 AR from a RS Topaz. so, i don't think it is a good choice to stack ar.
for manticore, if your weapon have affix "weapon damage %" > 40% then it is good to slot in 1 green + 1 ruby. if not, then better to slot in 2 green.

My DH's manti has 46% Damage so a ruby and an emerald marquise gems are placed into the 2 slots available. Check it out!

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i'm a no pro monks , currently farming stucks at mp 7 , coz gear now too expensive to upgrade   

http://d3up.com/b/1192659#gear

Bombardment is the best.
Forget about high velocity rune as the proc rate for pierce is pretty low (if you compare it to Wiz' archon).

Yes, you'll need higher AR or EHP for RF build.

Drop passive/vengeance. You don't really need it.
Use dps boost skill instead, steady aim / archery / cull the weak.

Try replace vault with smoke screen/LF. The benefit of using it smoke screen is your snapshotting will not be interrupted.
Try replace MoD with calstrops/BtT. The benefit of using it is it slows down mobs (better chance to dodge? Fewer hits from mobs?) + higher damage + higher generation of discipline.
P/S
I use Nat's ring/cloak + IceClimbers for bola/spike trap build.
I use Nat's ring/boots + Inna's chest/pants for RF build.
I found 10-12% melee damage reduction is very important for RF as it mitigates damage from explosions (fatty & elites)/arcane sentry.
This is especially you'll unlikely move around with RF build as you don't want to interrupt your snapshotting.

Throwing grenades will generate hatred, even if your grenades hit blank. 

Yes, you can tank very well with RF build.
I have to tank any way when I play solo. 

Thx guys. for the advice.

I tried grenade but i prefer to farm act 2. Grenade is icky when trying to kill those bees. With bola i could track them shoot few rounds and be on my way when it explodes. Bola/spike can mostly perma stun all day.

Is farming act 1 far better than act 2?

Oic~so this is my setup.... Any advice on my gear???
http://us.battle.net/d3/en/profile/LokkyX3...8/hero/38423967