Removing epoxy
Elmer,
Remove as much of the epoxy as you can with sharp knife. sandpaper etc. Don't get too close to the metal, you might scratch it.
Next wet the remaining epoxy with pure acetone. Wear gloves if you use a rag or use a small paint brush or a plumber's acid swab.
Keep the epoxy wet with the acetone and it will soften enough for you to scrub it away. If you let it dry it will harden up and you will have to start over.
Don't bother with nail polish remover, the acetone it diluted with water, scent etc. You can buy acetone at any hardware paint department. Canadian Tire sells a 500ml can that should do the job.
The acetone will not harm blued gun metal. However most scope have plastic trim rings etc which the acetone will dissolve if it touches them. And keep the acetone off of the glass, it may remove any optical coatings.
Beware of the fumes, acetone is commonly used by "sniffers" to get stoned. Keep it off the kitchen counter and use only metal or glass containers.