I recently sent in a Smith SEI model 2008 mount to be machined and reparked.

This was suggested by Mr Smith himself because he stated SA M1As have the mount area off a bit? This was because I wanted to get the best mount for long range precision shooting (2008 has the longest surface area for various mounting lengths to place the scope).

I do not understand, except he stated it should be done for optimum performance. I did not want to bug him on a long explanation.

Ideas?

V
OUT

SEI & SADLAK mounts are made to fit GI spec receivers... Springfield receivers are not GI spec.
Both SEI & SADLAK have methods to make their mounts fit M1A receivers... you're in good hands.

For the OP, one issue that may be involved is the location of the bolt hole on the receiver.  Harrington & Richardson Arms and Armscorp of America / Armscorp USA receivers have been found to have mislocated bolt holes.  The bolt hole on my 2006 Armsorp USA receiver was about 0.095 " too far forward.

GI spec receivers aren't a gold standard either. In the early 1960's, M14 Rifles were sorted through to find ones that a scope mount would adequately fit on. A lot were of unsatisfactory quality regarding scope mounting surfaces. When you have a large supply, you can find some that are perfect (sounds like finding a female companion).