One of the tweaks worth considering for the M1A/M14 is the installation of an adjustable gas plug. This is especially true in a suppressed configuration and/or for shooters that reload. Reloaders, in particular, will vary loads until they achieve the tightest groups possible. Here, the Schuster Adjustable Gas Plug helps in tuning your rifles performance to a particular load.
I recently had the opportunity to test the Schuster Adjustable Gas Plug. You can read my review below.