The retained weight is 151.7 grains. You may be right about the handgun bullet... Notice the lands are nicely engraved forward to a very hard line... like the typical step on a wadcutter. Probably what you noticed?
It is flattened to about .25" and widened to about .40" with the flat side very flat and the domed side quite low. In other words the whole bullet has been greatly reshaped and the domed side is not part of an arc, but much flatter.
I would still think 30 caliber, but it might be 32... I doubt seriously that it could have been 357. The smear marks on the back side actually look pretty cool and I should take a photo of them.
