Mick;
This one is not a DR. It's a Ruger No. 1 rebarreled.
My DR went down the road when I sold most of my rifles to
start a new company. Regulation changed with I played with
750 to 650 to 560 gr. bullets but I was always able to
regulate any size bullet, it just took a bit of work.
Reloader 15 is my friend. If you're looking for a 650
load in your rifle, I settled on 120gr of RL15, dacron,
Fed. 215 and the Woodleigh 650. 2050 fps in both the Ruger
and the Nitro double.
Hope this helps
Raff