Impossible Question as im not an IW Employee how the F*ck would I know why they did'nt put it in :p

Unfortunately, we don't have infinite time and resources. We can't just "put a gun in MP", guns in MP are an "all or nothing deal" and require a substantial amount of extra effort to add.

Gun for SP:
- model
- texture
- animations
- settings
(attachments, camos, etc... are all optional)

Gun for MP:
- model
- texture
- animations
- settings
- additional models (attachments)
- additional animations (to support different attachment)
- additional textures (camo)
- additional settings (each attachment has it's own setting)
- balancing (for each variant)
- additional images (Create a Class image, Obituary Icon, etc...)
- challenges
- titles
- emblems
- addition memory (everything above uses extra)
- anything else I forgot

To give you an idea, with attachments there are 10 variants of each LMG. When you add in Bling there are 40 variants. Time to test and tune these is not free.

Infinity Ward Staff member

So basically they are lazy.

If you read it you would have realized that with everything new they are putting in the game they did not have the time to put in certain guns, not because they are lazy.