Ok thanks for the informations.
I just looking the wiki for creating weapons (http://community.bistudio.com/wiki/Arma_3_Weapon_Config_Guidelines), I think it's easy to found more information and tutorials to built weapons from scratch, no ? Cause, I like the M40A5 and the L96 AWM, and as I'm a 3d graphist (ok, was, now I'm Technical Director for 3D departement... but still do modeling and co), I would like to built this model.
In all ways, Thanks for your answer.
Matt