Since that Model 19 has no pin in the barrel, those Targets likely came on it from the factory. They are quite nice and have some value on their own. If you remove them because they don't fit your hand well, you should stash them away in a safe place.
Here is a picture of a Model 19-3 wearing period-correct Magna stocks. The gun came with Targets, but these worked fine on this gun. It now wears walnut Targets again . . .
