I recently bought this rifle (Clayton Nelson pre-64 M70 in .416 Rem Mag) and it came with these scope bases. Any idea what they are? I originally thought they might be Talley QD bases, but they don’t look anything like current production. If you look closely, you can see they are part of a huge monolithic base. Very nicely done and I’d like to keep them, but I need to find the right rings for them. Thanks in advance.