Forget about the so called "realistic" weapon modifications - they are neither realistic nor necessary.
One of the most hated things about vanilla weapons is that their accuracy sucks bigtime rather than just a little.
This minimod changes the accuracy of ALL weapons by decreasing the dispersion by 30%.
To balance this zoom swaying (AMK/OL style) is added and this way shooting doesn't get that much easier - it may even be more challenging.
In addition to accuracy you also get 15% damage increase for all weapons.
As I wrote on GSC forum I think that this is the "sweet spot" where the game becomes more fun and rewarding but without losing its balance. I could go on about how and why but I suggest instead that you try it yourself.
NOTE: This doesn't modify the individual weapon files - only one weapon related file (weapons.ltx) is modified.
An adjustment tool is included - examine the readme in the tool archive file.
Download: http://zhat.dk/stalker/files/ballistics_tweak_v1.0.zip