The weak point of the '52 action in my opinion is the side lever bracket attachment to the cylinder. It has never ever given me a moments trouble with mine but across the pond where these are throttled up a notch I can imagine there is a lot of tension at this point and I just wonder if there have been failures at this junction? Over here I cant imagine there would be many (if any) issues.
Also with the same action and for the same reasons there is a great deal of tension and force being exerted via that little pin that is bolted into the front of the compression tube (cant recall exact name for this part).
Those are the only weak points in an otherwise robust action. But there again- have you heard of these parts failing in a wider sense?
Dave