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The Ruger website, under Customer Service, has a downloadable owners manual for your Mini 14.
580 is the newer version of the Mini 14 Ranch, minor engineering changes, improved accuracy, etc.
$350 to $800, depending on WHICH Mini-14, and condition.
If you go to Ruger's website you can download the manual for your mini 14 for free. It tells how to disassemble your gun in the manual.
You can contact Ruger's customer service to find out.
Ruger has sn data on its website.
It says it can on Ruger's website.
You will have to call Ruger.
Alot of Bucks.
You will have to call Ruger for the age; 100-400
Call Ruger and they will tell you.
100-599 depending on specifics