There is 2 faces on the Head of the Crimping Tool.

There is a Magnet that holds the Link in place until the Link starts to be pressed over the Pins and that face pushes the Link onto the proper position.

Your then remove the Head of the Tool and reposition it so that you can use the Crimping part of the Tool.
Both of the Pins get crimped at the same time and the same amount of Crimp preventing one end of the Link from getting peened tighter preventing the Link from going on crooked.

How well Link Pins peened with a Ball Peen Hammer comes out is going to depend on the skill and attention that the doer is able to put into the job.

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84 300D, 82 Volvo 244Gl Diesel