delia 1
Start with loads for a 22 Nosler. The Nosler has a head to shoulder dimension .126" shorter than the 224Wea. Since the Wea. holds more powder,
and has a larger bore then the Nosler, starting with loads for the Nosler should be OK in the 224x6mm
Powders such as VV N-133 and 135, 4895, 8208XBR and maybe 748 should be good choices.
Start light and work you way up. If you have a chronograph, that would be a great help in developing loads. I would expect your 224x6mm to max out at around 3400-3500fps with a 65 -68 gr. bullet.
The above info assumes your barrel is a 14" twist, if it is faster, watch if pressure become excessive from a faster twist. This would be most likely with 8" and faster twists. I am not sure what twist was common to the 224-6mm.
Hope this gets you started,
Steve Kostanich
PS. I assume your 224-6mm is not on a shortened version of the original 224 case. Check to make sure your 224-6 is chambered for a full length version of the 224-6 case.