In People v. Wandick (1991) 227 Cal. App. 3d 918, the People conceded that instructing the jury regarding the Penal Code section 12091 presumption was error, but argued it was harmless under Chapman v. California (1967) 386 U.S. 18 87 S. Ct. 824, 17 L. Ed. 2d 705, 24 A.L.R.3d 1065. The court disagreed, distinguishing presuming a state of mind from the underlying fact with presuming an act: "It is one thing to infer intent from a criminal act. It is another matter to infer a criminal act (obliteration of identifying numbers) from another act which may or may not be criminal (possession of a weapon with obliterated identifying marks). Even if the jury found defendant possessed the revolver, that fact standing alone is not sufficient to support a finding beyond a reasonable doubt that defendant obliterated the numbers. Since there was no evidence, other than circumstantial evidence of possession, that defendant obliterated the identifying numbers on the revolver, the erroneous instruction cannot be found harmless . . . ." ( People v. Wandick, supra, 227 Cal. App. 3d at p. 925.)