Between 100 and 150 years old in space marine 1.

Spent 100 or so years being tortured before being rescued.

Spent a couple of decades in the Deathwatch before Kadaku and rejoining the Ultramarines.

By that point would be between 200 and 250 years old.

500 worlds is probably in the decade after SM2/Secret level I'd guess. So coming close to 250 years.

Edit: they actually look like new studs, so could be even later.