Go there. Read. Learn. If it is SKS related, it's there.
A no date Tula star receiver cover? Who knows when it was made, but historically people thought 55-56 for no dates. Not so sure anymore. If it was refurbed, it could be mfg from 45-56 I reckon.
A free people ought not only to be armed and disciplined, but they should have sufficient arms and ammunition to maintain a status of independence from any who might attempt to abuse them, which would include their own government." - George Washington, January 8, 1790, First State of the Union Address