I lately noticed that perk check disabling has a bit changed for some perk in SP/Survival mode. This might apply to Multiplayer mode as well. Perk check disabling are used to apply specific perk effect without equipping it.
I will take perk_WeapReloadMultiplier as an exemple.
To make a fast reload cheat in the newest Steam patch of MW3, you will need to patch 3 things though 1 is optional.
In previous MW3 patches, the reload speed and animation were used in the same opcode so that you only need to patch 1 opcode to make it work. Now, Reload Animation and Timer and separated but uses the same Float value. Some "Perk_" might only need 1 changes like in previous patches but i'm not sure. Not tested yet.
1: Reload Float Value ---> Read Float value of 0x1D398E8+C. This will give you the reload value that you can edit. Higher the number, the slower is the reload.
2: Disable Perk Check for Reload Timer ---> Write EB 00 (Hex) or 235 00 (Dec) to 0x00647770
3: Disable Perk Check for Reload Animation (optional) ---> Write EB 02 (Hex) or 235 02 (Dec) to 0x005770C9