Go to Ruger's web site and request a manual.
You can request an owner's manual for free on Ruger's web site.
You go to the Ruger website, Customer Service, and download the Owner's Manual. There are also several Youtube videos on this.
You can request a manual for free at Ruger's web site.
Take it to a gunsmith.
Narrow down your request please. Rifle ie 10-22, pistol, etc..
Find a good gun smith.
What Model 51 pistol or a rifle and what model?
Find a gunsmith and ask for help
Best left to a gunsmith.
Ask a gunsmith for help
if a pistol, tnen the same way as the military 45 cal pistol