America’s largest gunmaker, Sturm Ruger & Co., accused the parent company of Italian arms firm Beretta of trying to stealthily seize control of the Connecticut-based business through “self-serving demands” such as cut-price stock buys and veto-like board power. The Todd W. Seyfert-led giant hit back on Monday at the historic firm’s proxy fight, which was first reported by The Post on Feb. 25 , that branded the move as a thinly-veiled threat to launch “a war” and complete a full takeover. A