I agree, while you're typical commercially available AR is not an assault rifle (the STG44, AK47/74, and M16 are because they are lightweight full auto weapons) I think the MSR term is quite frankly silly and a feeble attempt to make the 2A crowd more PC (no offense meant towards those using it, I like you guys just not your term).
The anti crowd needs to get used to the fact that we're here, we and our 3+ million firearms are not going anywhere, and neither is the 2A. The infringement stops now.
*edit-
Google definition of infringe-
Verb
1.) Actively break the terms of (a law, agreement, etc.): "infringe a copyright".
2.) Act so as to limit or undermine (something); encroach on: "infringe on his privacy".