If you send me a PM I can let you have load data for the 7x65r for a number of powders including IMR 4831 and 4350. The Hornady manual has quite a few loads for a range of bullets from 139 up to the 173g.

I would give some of these a go and you might get lucky and replicate the factory regulation.

I suspect that the factory regulation would be done with RWs 173gn load. An email or a call to Chapuis would be worth a try.