I don't know...unsure if I'm that disturbed by the issue which ever way it goes. However, I would think the variant category might be better defined as AR15 platform and AR10-style platforms. I have two Armalite AR10's, but I see them in the same category as every other non-AR15...DPMS LR308, GenII, etc. Being somewhat new to the AR style rifle, I may be looking at this completely wrong. I see the AR15 platform as containing any caliber that uses the AR15 with the basic milspec dimension construction...5.56, .223, 300-BLK, and all those calibers that fit the traditional AR15 milspec weapon platform. When the gun has to notably change construction dimensions to accept larger parent case calibers...7.62 as the most common but all those larger-than-5.56 that won't fit the AR15 without notable manufacturing alterations...I think you have that AR10-style weapon at that point. To simplify, I'd say if you can change the caliber of your AR15 platform with just a barrel change...generally...then you have an AR15. Just about everything else would be a variant. This is just an opinion and observation on my part. Others may have a better perspective on this.