I tested every kind of weapon in a custom game, strafing full-speed (while ADS with Ghost) in both standing and crouching positions, and with every combination of the Adjustable Stock and (via Perk 1 Greed) Lightweight factored in. Based on the results from whether the minimap arrow faded or not, and assuming all weapons in the same category have the same base movement speed (which I'm 97% sure they do), here's what I discovered:
+ Assault Rifles can only activate Ghost when you have the Stock equipped, whether standing or crouching. LW has no effect. + Submachine Guns and Pistols always move at enough speed to activate Ghost while ADS no matter what the circumstances. + Shotguns almost always get the benefit - the only time they don't is when they're crouching and not using either Stock or LW at all. + Lightmachine Guns only move fast enough to activate Ghost when they have the Stock and are not crouching. LW has no effect. + Sniper Rifles, Launchers, and the Crossbow can never move fast enough to activate Ghost while aiming down the sights.
Remember, this is when you're strafing at the maximum speed possible while aiming down the sights, so if you slow it down at all your results may be different. Hopefully this information helps all non-camping Ghost users in their future games.
Not changing this line of my sig until (The) Ryback's hunger is satisfied - started 9/24/12 http://i.imgur.com/PMzJP.jpg