That's a 500 Jeffery on the 550 and a 510 ASquare on the 602.
Pay attention to the triggers, they are both set triggers, and see how they are attached below.
550 trigger is attached to the receiver.
602 trigger is attached to the floorplate.
The 550 trigger, when in set position, operates much more smoothly and with less noise than the 602 trigger in set.
More photos later.
Good shooting! H
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