MacGregor Golf is said to be undergoing changes in top management. F. Duffield Meyercord, a partner in a venture capitalist firm, Carl Mark Advisory Group LLC, and past president of the Baltusrol Golf Club, will take over responsibility for MacGregor’s day-to-day operations from the company’s chairman and chief executive, Barry Schneider, who still owns 60 percent of it. The reasons for the change could not be determined.