Acually it's about 1wt%, which makes it about 150% stronger than aluminum.Sort of.
Scandium is actually heavier than aluminum by volume.
Sc density 2.98
Al density 2.70
Scandium is a very rare, very expensive metal that is added to aluminum in very small quantities to make very strong aluminum alloy. So when you buy a Scandium gun , you're actually getting an aluminum alloy gun with a trace of scandium.
Your "Scandium" frame is something like 1/400th scandium and 399/400th good marketing!