If you own an AR70, I'd call Berretta - most manufacturers are willing to provide manuals for free as a precaution against liability. When I bought a used Sig P226, I called Sig USA and they sent not only a manual, but a P226 box with the foam lining.
If that doesn't work, try posting an ad on the appropriate ad board at either subguns.com or sturmgewehr.com
