I agree with BattleRife. Brownell's was able to deliver their BRN-10 rifle for an affordable price because they accomplished a largely cosmetic clone of the Cuban variant of the Dutch AR10. The BRN-10 product manager and I had many email exchanges and he admitted to using photos as a reference since they only had access to a Portuguese AR10. Lucky for you Canadians that the upper-lower mating profile and location of the locking pins are unique to the BRN-10. Just look at the exaggerated carry handle on the BRN-10 and it is a reminder of the Hollywood Model AR10. The charging handle stickiness of the BRN-10 is not inherent to the early trigger style design. Brownells choose a cheaper and simpler retaining method as compared to the more complex detent used on Hollywood and early Dutch AR10s.
As for the AR102 Sporters. I have inspected several different authentic AR102 rifles and again BattleRife is 100% correct. The US ATF demanded that several changes be made to the AR10 platform before semi-auto variants could be imported and sold to the public.
1) The gun could not be called an AR10, so Armalite toyed with AR100 and settled on AR102 name.
2) Military magazine could not function with the semiauto. So Armalite installed a block in the right side of the magwell to prohibit military mags from inserting.
3) A steel sear blocking pin must be present, much like Colt used during the ban years on AR15's.
This is what a real Cuban variant AR10 looks like. The brother to this gun lives in Toronto at "Movie Armaments Group" Toronto. The one below is in the US and is intact.