The .17 HMR is pretty much a necked down .22 mag round. I think they started selling the ammo and rifles for it in 2001 or 2002 so not too long ago.
As far as the plastic tips go this link could help explain it.
http://www.gunsandammomag.com/ammunition/plastic_fantastic/
I didn't read most of it so hopefully it helps
As far as the plastic tips go this link could help explain it.
http://www.gunsandammomag.com/ammunition/plastic_fantastic/
I didn't read most of it so hopefully it helps