All these reasonings I think in will not result. Q3 engine is too complex. I will add only the one that is confirmed by experience: my shots are exact only when values of variables mpitch and myaw come to an end with a number in the period and have 6 signs after the comma.

I've found this

http://www.esreality.com/?a=post&id=1638450#pid1638450

R = ( pi * W ) / ( I * tan[ F / 2 ] )

where

W = screen resolution width

I = real sensitivity (distance per 360 turn)

F = horizontal fov

R = mouse resolution required

.xls is here http://www.esreality.com/?a=post&id=1681607#pid1681607

but when we have fixed DPI on mouse I think we should play only with our m_yaw, m_pitch and sensitivity so:

I = 360 / ( M * S * DPI )

from 1st equation

I = ( pi * W ) / ( DPI * tan[ F / 2 ] )

then

360 / ( M * S * DPI ) = ( pi * W ) / ( DPI * tan[ F / 2 ] )

M = ( 360 * tan[ F / 2 ] ) / ( pi * W * S )

where

S = Sensitivity in game ( Windows sens default )

M = maximum values of m_yaw and m_pitch to get 1px precision for given S

OK, injx said it's correct

i will re read again this topic and also that website and make a tests....as now i cant find a sensitivity for my new mouse :'(

my post was wrong

there is no such thing as pixel precision in FPS games

from esreality.com

"you're right, it's just a model (only we have?)
with default windows sens and no mouse driver scalling m_yaw/m_pitch are elemental angles that 1 mouse tick rotates the scene we see and ingame sensitivity is simply a multiplicator of those values

so we should calculate m_yaw/m_pitch - values should be smaller than angle between lines connecting observer with edges of object (like enemy head) placed in maximum distance we encounter in particular game that would be represented by at least 1px at a given resolution
right?

without good knowlege of game engine that's impossible
and maybe mouse DPI would matter if m_yaw/m_pitch were really small :]

in conclusion: set all settings way they fits you and look at configs of best aimers :]"

Here you have code responsible for mouse movement:http://pastebin.com/v0LfetG8

So if we make assumption that accel = 0 then view angles are calculated in this way:angley = mx * some_const_based_on_current_fov * sensitivty * m_yaw

Simple equation there may be only loss in accuracy when rounding number but it should not matter what sens/yaw you actually use. Scaling that depends on fov is probably to make sensitivity feel same way between different fovs. m_yawspeed, m_pitchspeed it’s for keyboard handling (epsi).
And yes 1 cpi can be 6 pixels based on this equantions and there is 3rd multiplayer as you said but evenwithout it you would not have 1px jump it need to be scaled for proper angles.