Argentina did something similar in the 90s. Not with precious metals, but with a strong currency (the dollar). It did stop inflation, but, after a decade, it had to be abandoned, because it was too restrictive. Of course, if politicians would have been less corrupt, or better at making decisions, maybe it would have worked longer.

In principle a precious metal currency could inflate — if someone finds more gold and silver. There are semi-plausible proposals for asteroid mining.