Edwin J. Gray, chairman of the Federal Home Loan Bank Board, cautioned the House Banking Committee against putting off for six months a new FHLBB rule requiring thrifts insured by the Federal Savings and Loan Insurance Corp. to receive permission before putting more than 10% of assets into real estate purchases or other direct investments. The rule went into effect last week, but more than 230 members of the House have co-sponsored a resolution to delay it. Gray said "responsibility . . . would fall squarely on the Congress itself" if the FSLIC was further weakened because it could not control risks by the institutions it insures.