This from Degoins at AR:

Posted 15 January 2010 19:10 Hide Post
Here ya go Bill.......Caliber: .450-400 NE 3” (400 Jeffery)
Barrel length: 24 to 26”
Powder: Accurate -- 5744.
Bullet weight: 210 grains.
Reduced load: 37.0 grains (1650 – 1750 ft/p/sec)
Midrange load: 47.0 grains (2200 – 2300 ft/p/sec)
Maximum load: 60.0 grains (2750 – 2850 Ft/p/sec)
Bullet weight: 300 grains.
Reduced load: 36.0 grains (1650 – 1750 ft/p/sec)
Midrange load: 50.0 grains (2175 – 2275 ft/p/sec)
Maximum load: 55.0 grains (2275 – 2375 Ft/p/sec).
Bullet weight: 350 grains.
Reduced load: 33.0 grains (1550 – 1650 ft/p/sec)
Midrange load: 44.0 grains (1850 – 1950 ft/p/sec)
Maximum load: 52.0 grains (2100 – 2200 Ft/p/sec).
Bullet weight: 400 grains.
Reduced load: 30.0 grains (1400 – 1500 ft/p/sec)
Midrange load: 40.0 grains (1700 – 1800 ft/p/sec)
Maximum load: 49.0 grains (1900 – 2000 Ft/p/sec).
NOTE:
It’ important to note that:
Whenever Accurate Arms do not test, and have actual data, on a particular caliber or caliber/bullet combination, we may in some cases provide some guideline. This information will be based on various procedures and calculations, or from other very reliable sources.
1. SAFETY is our prime concern therefore:
1.1. The loading data is conservative, especially regarding the minimum or start load to ensure a safe baseline to work from.
1.2. The safety margin built into the start load might be more than the customary 10%.
2. We strongly recommend.
2.1. To always start at the recommended minimum “START” load.
2.2. If at all possible, measure the velocity.
2.3. Contact us again with the velocity data, so that we can verify, and correlate with our calculated/estimated data. The data should also be compared, with the typical velocity levels accepted in the industry, for that particular caliber-bullet weight combination.
Regards
Johan Loubser
Ballistician
Western/Accurate Powders
Tel: 1800 497 1007 or (406) 234 04 22
Part of Western Powders -- Miles City Montana
For all Sales, Marketing, Pricing Distribution and related issues, please call toll free 800-497-1007.

I've tried the mid range 210gr loads and they work great in my No.1 and my Searcy. Havent tried the 300 gr loads yet.