I have a 2015 300C and I looked and looked for a manual for it. I ended up ordering the manual on CD from Chrysler for $150.
It is the manual that the dealers use.
I actually think a Chiltons would be better than the one from Chrysler. But this is the only thing available for the next few years, Chiltons and Hanes usually take 5 years or so to come out with manuals for newer cars. I think they wait until the warranty expires on the vehicle before they release one. Thats the only reason I can think of.