Greg Downing (left) standing in front of the RF generator (circa 1978) that he used to melt the Canyon Diablo iron meteorite (right) and discover evidence that a) iron meteorites trapped "normal" Xe rather than "strange" Xe, and
b) minerals in iron meteorites were pre-irradiated by cosmic rays prior to compaction. 
The ratio of spallation products does not simply indicate size of the meteorite parent body during later exposure to cosmic rays.