Finally found my reply from Accurate Arms Powder, here is the load data they sent for my 500 Jeffery shooting 525 grain Cast Performance Bullets with AA 5744. I'm buying myself a reloading notebook for Christmas lol ...

We suggest the following.
Caliber: .500 Jeffery - Rimless.
Barrel length: 24”
Primers: We recommend using only Winchester Magnum WLRM or Federal 215 magnum primers.
Reduced loads:
Powder: Accurate – 5744.
Bullet weight: 525 grains.
Low load: 55.0 grains (1600 - 1700 ft/p/sec)
Mid range Load: 65.0 grains (1825 – 1925 Ft/p/sec).
NOTES:
It’ important to note that SAFETY is our prime concern therefore we strongly recommend.
1. TO ALWAYS BEGIN LOADING AT THE RECOMMENDED MINIMUM “START” LOAD.
2. If at all possible, measure the velocity and correlate with our data.
Regards
Johan Loubser
Ballistician
Ramshot/Accurate Powders
Tel: (406) 234 04 22 email: johan@ramshot.com
Western Powders Inc -- Miles City – Montana.