A gun that is built to spec will have the link pin staked in place.
Built to spec, the pin is a press-fit. Staking is unnecessary, and is usually employed as a field expedient repair to prevent pin loss during field-stripping.
Sorry, yeah, Kuhnhausen recommends two different staking theories. I thought it was a government publication. The Ordnance Maintenance manual says only to gauge the link pin, but doesn't say what to do if it's undersized.