Hi Jim, the class of so called 'spotted horns' seems to have been concentrated in the Berks County area. The butt plug usually has a knob and is nicely domed. The stained spots have a 'measles' appearance and usually cover most of the jacket surface. They were done in iron ferric chloride or other chemical. Seems to me that the Rajin Cajun posted some nice photos of a great spotted horn here not too long ago. You can refer to that for comparison. Then, as SP ventured, you can check Art's site and or/book. Like others here, I doubt that this one fits that standard category. It is till a nice horn and seems to have stippled designs. Have you found this to be the case? Thank you for showing it to us.
Dick