Aeg buffer tubes will be fatter then gbbr ones real steel parts fit on most gbbr.
As far as i knos there is one off brand of gbbr that uses mostly aeg parts but for WE's im prety sure its RS stuff you want.
Now that doesnt mean it wont fit but itll be loose and may not lock in place.
Also for RS there ars two types of tubes/stocks a "mil spec" and a standard/civilian type so youll have to find out what one the gbb has. As far as i know the civi stocks will fit on the mil tubes but the mil stocks will be too tight on thd civi tubes.
Hopefully someone with more hands on knowlage can chime in

Yes I ran my hk416 style stock on my WE Hk416.

so there is no issues with getting my ''items'' here into canada? im not buying a gun just getting the Stock, and some small gear.

also, since they are so far away from Alberta...what is the best delivery method? and does anyone know how much all the other fees will add up?

never delt with someone so far away...makes me nervous.

Duties are sort of varriable but half the cost of the items isnt unheard of. I once payed 60 bucks dutie on a 40 doller chest rig. And only paid 30 on a 300 doller gun (omgwtf lol) so it all depends. And yes youll get it you only cant order mags with fake bullets lower recivers (unless its the upper that is the restricted part like on an mp5) and pistol frames.

perfect, thank you very much.