Have you got a parts diagram? The booklet that comes with the H5 usually has two exploded view diagrams, one manual, one semi. There are some new parts and IIRC some to be replaced.
Now that he has the green light I guess there's no reason why HP should not be involved; he might want to do the work rather than supply the parts and that's maybe not a bad idea, the semi version does need some setting up. The clearance between the front face of the magazine and the back face of the breech is crucial to get right. Steyr have a video on the home site showing how to do it.