HelpNeed Help With Installing Model Change Mods

Ok, I am very new to modding. I understand how to inject and everything. I already modded textures and sounds and scopes, but i have problem with model changes.

I particularly wanted to install a mod (HiddenMaster of FSP™ and EFSP™ Desert Eagle SE to G23 Carbon Black) but I have problem. When I inject everything into the right rez files, when I go ingame with the Direct combat arms, it tells me that client has been corrupted. It doesnt happen that way with texture mods, scope mods, sound mods, etc.

Any help? Thanks

rename the new rez file to texturescripts.rez and replace the old one and it should work