The 9.3-66 is just a lengthened 9.3-62 case and Sako does their velocity tests out of a 28'' testbarrel,wich is actually a polygon barrel.thus velocity is even better than with an average barrel.Velocities appear very promising,but practically they are different.I shoot a 9.3-64 in a Steyr-Mannlicher ST and a 25"barrel and using 67gr of Rel 15 with a 250gr Ballistic-Tip,i get about 2850ft/sec.A friend of mine,who lives in Austria just bought a Sako in 9.3-66 and he gets with the same bullet about2680ft/s,so as you can see,it does fall short of the promised velocity.I think the 9.3-66 is an improved version of the 9.3-62.Nonetheless a splendid choice for the avid Big-Game hunter.
When it comes to brass,right now there is only RWS brass readily available,but Russia just intoduced a new Sniping rifle in 9.3-64 and they have already started manufactoring there own,but i don't know if it will be available for the civilian market soon.Rws brass is very tough and i used some 25 times and there is no sign of them getting worn out.They are a bit pricey over here but i get them sent from a gunsmith in Austria and there they are way cheaper than in Canada or the US.Well,i hope i was of any help.Happy hunting and shooting. :grin: