The new $300 is going to be a 6 ounce center with a gold plated brass rim. Same size as the other $300 or the $200's.

My local coin store will buy the strikes that do not say .999 on them such as the silver inserts from the old $10 strikes once they are removed from the brass rims. However, he pays a buck less per ounce, not per strike. So he would buy your strike but would pay $12 less than he would if it did say .999 on it.

Hope this helps and if I am wrong on any of this I am sure someone will jump in and make it right.

Dennis