After a jury trial appellant was convicted of having violated 21 U.S.C. §§ 173, 174. Though no objection was made below, appellant requests us to hold that the method federal agents followed in entering premises where appellant and others were found processing narcotics was “plain error” within the meaning of Rule 52(b) Fed.R.Crim.P. inasmuch as appellant claims the entry violated 18 U.S.C. § 3109 and the Fourth Amendment.

We find no reversible error and affirm the judgment of conviction entered upon the jury verdict.