Link: Earlier versionIt appears to be the early version that SAI used on the M21, before using the one from Boyd's. Yours would have been made in the '90s.
Is it inletted for a rear lug? Does it have grooves for bedding compound?
Thank you the info!Link: Earlier version
and another: https://www.m14forum.com/threads/custom-built-m21-have-to-sell.185948/#post-1624543
Link: Newer version (both versions discontinued)