Gentlemen,

I had the nice experience to meet the originator of the cartridge, Mr. Werner Reb at a shooting course where he was the instructor.

He made also some claims about this cartridge and I was also, like you, not convinced.

But Mr. Reb invited me to a special precision shooting competition for hunters and hunting rifles, where only rifles in 8,5x63 and the rimmed version, the 8,5x63R were allowed (no match rifles!).

As loaning rifles were Blaser R93 available(I succeeded to avoid contact with this %&$§%%&/&%), Mauser 98 and Mauser 03, equipped with scopes form Svarovski and Zeiss (10x/12x and 14X magnification).
All rifles shot very good groups at 100m, 200m and 300 meters
(ammunition was the Jaguar 12,5g solid copper hollow point bullet from LFB company).

Recoil was manageable due to the 24" long (medium diameter) barrels.
Precision was nothing short of fantastic for me, because it was no problem to obtain a 5 shot group measuring 4"/300m!
The best shooter had a group (5 shots) 5,5 cm at 300meters!

So, for the next competition I dream of having a rifle in this caliber, either a Heym SR20 or a custom Mauser 98 with a 24" barrel.

Other competitors reported having good results with Accubonds and Barnes TSX for fox, roe deer, pigs and red stag.

I can provide more information about this caliber, please send me a PM.

best regards
Rolf

PS: Best results in forming cases for the 8,5x63 can be had from 35 Whelen cases.
Set back the shoulder in small incements and test for bolt closing in your rifle.
Then load medium burning powders (no starting load!) and a cheap bullet for fire forming.