I'd like to see some graphs of ammo sales over the lifespan of these various calibers.
I'd bet you'd see some mind blowing numbers with the .17
The .300 not so much
IMHO, that's the correct answer. The 17 HMR had three advantages to help it's sudden rise and sales: 1. A round that was completely different from anything else in the market at the time. 2. It's a rimfire. Rimfires are MUCH less expensive to shoot, and easier to shoot for lots of folks, than are centerfires. 3. Different segments of the shooting community bought and shot it. While the 300 BO has been extremley popular in the TACTICAL community, there are many more non-tactical shooters out there than tactical shooters. If you ask all the shooters at my work place about the 300 BO, the typical response will be, "What did you say?" Ask them about the 17 HMR and they'll start smiling and say something like, "I really do like mine!" I don't think the number of different platforms a round can be found in plays a significant role.
I'm surprised no one's posted a link yet that shows annual sales of factory rifle/handgun ammo.