You will never find any law/reg that says "it's OK to purchase a Glock FTF", as no such thing exists.
If you read the law and regs, you will see that they were written as a restriction on "purveyors" (licensed dealers) ONLY. Thus, mere subjects are free to trade any brands/models that they own.
I'm pretty sure that the AG Regs are online, but the new AG re-did the entire website and thus old links are non-functional. I'm working remotely off a laptop with a slow link today, so you'll need to do your own searching.
"A man who trims himself to suit everybody will soon whittle himself away." - Chinese fortune cookie (but politicians should take note!)