Have to laugh that the weight they report lacks the tripod collar.
It's the same for every single manufacturer - advertised lens weights never include caps, hoods, drop-in filters, or tripod collars (or removable tripod feet). Some of them are so far from reality I think the marketing department fills the lenses with helium before weighing them.
Even in the box the FG 500/5.6 body is separated from the tripod mount.He,he.