I just got my first pound of Reloder 17 a couple of weeks ago and haven't had time to wring it out yet. In fact I am still trying to decide which cartridges to try it in...
The only thing I would add to the foregoing is that while I have also used H414 (or Win. 760--they are exactly the same powder) in the 7x57 with excellent results, I would warn that in really warm temperatures the pressures can get a little weird. It is a classic ball powder, and these can increase pressures considerably in ambient temperatures much over 80 F.
Of course most of North American big game hunting is done in cool enough temperatures that this doesn't matter. But 14 years ago I took a custom 7x57 on a pronghorn hunt in New Mexico in in the last week of August. The load was a maximum charge of Win. 760 and a 140-grain Nosler Ballistic Tip, and while there were no real problems, that hunt was one reason I switched from 760/414 to H4350 or Ramshot Hunter for most of my 7x57 hunting--especially in warmer weather.
