First thing to do is to make sure Auto-Target is either off, or (in my case) can be turned off with a press of a button.

The best time to practice with Alchemers would probably be something like the Royal Jelly Palace (Or Firestorm Citadel if you know that place like the back of your hand), where you can get several decently large mobs of Slimes (Zombies with FSC) with plenty of space to outrun them. Most of it is simply stuff you have to get used to, and it's hard to put down on paper how exactly to use the bounces (It's like teaching someone how to throw a baseball when you can't see or hear them, relying only on text and maybe quick scribbles).

They'll always bounce to the same direction, as Bopp said. I use mainly charge attacks (With Seerus' Mask and Chaos cloak for maximum CTR), so I'll just comment on them. It's all about "nestling" the shot in the middle of dense groups. Zombies are a bit easier to deal with. I'm pretty sure there is a mission that starts you at a Tier 3 Graveyard... I *think* it's "An Occurrence at Owlite Keep" but I may be remembering that wrong. Basically you want to the shot to hit/detonate when it is surrounded by enemies.

Quick Scribble:

T = Target(s) to aim at
E = Enemy(s) to kill
K = Knight/You

- - E T T E - -
- E T - - E E -
- - E - - - - E -
- - - - - - - - - -
- - - - - - K - - -

Hope this makes vague sense. My Nova Driver charge shots are doing about 500 damage, with the bounces doing 275 damage per (+dam Ultra). Get it right and the cup-shaped formation of enemies should absorb (almost) all the bounces for HUGE amounts of damage.

An exploit of all alchemers, internal ricochets when shot without Auto Target if you aim just right enough against your enemy.

Notes to keep in mind about alchemer ricochets:
Ricochets always go to left within a 90 degree angle of the prior trajectory.
Distance stands chance to affect ricochet probabilities (the further from enemies I am the more often the ricochet is about a right angle, the closer I get the more the shots seem to just bounce right back in my direction (still have oddball bounces))
Charge shot has a set angle for the first series of bullets to ricochet, then those bullets ricochet as per normal bullets.
Auto target is the bane of all alchemers.

You strafe and you shoot and you angle it in such a way and you shoot some more and then you strafe some more. If you strafe around but not in the wrong way then the enemies will get shot more and if you strafe around but not in the right way then enemies will shoot bullets off the wrong way because you are not.

But mostly you need to aim in the right place as you strafe and you need to make certain to hit them. And if you use a charge you should hit slightly off center because you can deal damage and win and this is good. But if you don't then you should strafe and switch. Having two alchemers can be good but only sometimes.

In order to use an alchemer correctly, one must know a few things- that the bouncing orbs always ricochet on impact, so when in doubt, use auto aim! And they always ricochet to the left of where the projectile originates from. Also, they are best dps-wise utilized when switching weapons continuously while firing one shot for each switch, since they have a stupid two shot clip.

Also, the alchemers have practically one shot kills as charge attacks for the appropriate or lower stratums when aimed correctly, usually directly to the left/right of the target, and disabling auto aim. Also, One can utilize the reverberation quality of the charge to use trick shots to fire around corners and other places you are not supposed to see. Hmm.

In PvP, Alchemer spam is not as effective as Pulsar Spam, but if more than one person uses a driver, it can quickly go from inaccurate little men to big, fat, bullet upchucking machines. Assuming you can hit someone, at least.