I have a reference I can check and let you know if the number has any identification. Can you post which units the Coberly hits you have are associated with? Also, the 1860 Spencers in that serial numbner range were likely not in the hands of troops before Spring, 1864. If any of the Coberly records you've found show muster out dates before then, you can tentivly scratch them off the list.
I'll get back to you.