I would think it best to use no more compression than necessary to get it free from the lock. As far as forged against cast, the forged would be slightly less apt to break easily, but it doesn't have to be hammer forged, merely shaped red hot in its bends from bar stock is an equal. All steel will have inclusions, and occlusions. Steel grains themselves have no direction once heated after being rolled and finished in the bar forming process at the mill. The rollers that form the bars stretch, close, and compact any inclusions or occlusions, and stretch the grains in the direction of the roll, but once re-heated, grains re-form into haphazard shapes. What does add directional strength is that grains will collect at the borders of the directional impurities, similar to a stitched button hole, making tiny unit like structures. A casting will have no directional strength at all, but if well cast is only slightly less strong. Breakage in cast springs is almost always traceable to poor handling, and, or, occlusions. Gas or air pockets, or just poor casting.
