I load the 6.5 x 55, but I load it for M96 Swedish Mausers. Therefore, I don't go as high with the pressure as you could with a modern rifle.
Ken Waters recommends these loads for 140 grain bullets in MODERN
6.5 x 55's.
39.0 grains IMR 4895
45.0 grains H4350
I have actually tried both of these recipes and they're very consitent. I probably shouldn't have tried them in my M96, but I did. [img]/ubbthreads/images/graemlins/blush.gif[/img] No problems occurred, but primers were cratering considerably.
At 300 yards, with IRON SIGHTS, my M96 did this with the Hornady 140 grain Interlock and 45.0 grains of H4350:
A very accurate powder for the 6.5 x 55 is RL22. "Reloder 22" appears to be the same Bofors (of Sweden) manufactured powder formerly known as NC1220 (military spec). I've pulled down some of the M41 "Prickskytte" Swedish long range military rounds and examined the powder. 46.3 to 46.5 grains of the NC1220--but it appears for all the world to be RL22.
I took equal volumes of RL22 and the NC1220 and weighed them--they weighed exactly the same.
I examined the color and cut of each (under a magnifying glass), again, a perfect match.
I burned a pinch of each in an ashtray and noted that each powder had the same smell.
Lastly, I checked the load data for RL22 and worked carefully up to 46.3 grains of RL22 behind some pulled M41 bullets, and compared the velocities of factory rounds and my handloads with RL22--nearly the same, within the ES margin of each other.
The M41 Prickskytte round was a Norma made bullet of approximately 143 grains (they actually varied considerably, from the low 142's to about 143.5 in the ones I pulled). The best bullet to match that weight today would be Sierra's 142 grain "cruise missle" [img]/ubbthreads/images/graemlins/smile.gif[/img] Matchking. I've used that bullet with 46.3 grains of RL22 with excellent results.
Since you're interested in the 6.5 x 55, you might find this link intriguing...