Lon nailed it quite well. The aluminum lams were dropped in early '51.
It's been speculated that the ones that are going to delam have already done so. Your third picture is a great example of the alumilam limbs taking a 'set'. This one has been used quite a bit and/or left strung.
Less used '50 limbs are fairly straight, with the '52 and on limbs/handle showing a gentle deflexed arc unstrung.
Looks to be in pretty good shape overall