ΔE 10.5, fair: the same colour family, but not a straight swap. Semi Gloss Bright Gun Metal is a little lighter, more saturated than Leadbelcher.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 10). Semi Gloss Bright Gun Metal is a little lighter, more saturated than Leadbelcher.
The same difference applies the other way round: Leadbelcher is a little darker, more muted.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Leadbelcher on the colour wheel See Semi Gloss Bright Gun Metal on the colour wheel
All matches: Leadbelcher equivalents · Semi Gloss Bright Gun Metal equivalents