More like 1973-75.
They’re neat. This gun is identical to the Jager Dakota / Frontier that is more common, though it’s quite right to notice Hammerli’s gun was more handsomely finished by comparison.
Finding suitable triggers, hands, and springs is generally not a problem. You can use Uberti triggers, hands, and springs, etc. The screws are done in metric pitches though. If you bugger the screws you will be out of luck.
They are not common. Interarms probably brought in 3000 or so Hammerli Virginians in the early 70’s.