I own a SA M21 ( '96 ), It is a dream of a M1A. I got lucky and found a used one .... I saw it for sale and actually stopped in my tracks gawking at it.
Thankfully, The Gun Shop allowed me to make payments on it. Since I really couldn't afford the price.
It actually taught me to shoot better, it is precise enough to be able to tell when I flubbed the trigger pull or was fidgeting at the bench.
It loves the 168gr FGMM. However, if I don't keep the gas piston clean , precision falls apart after about 150rds.
It has the Douglas Hvy Barrel.
On a side note... I once tried to install a USGI vented handguard... and accuracy promptly went to poop.
As it turned out, I had no idea how much finessing SA had put into every part on the M21.
The Vented handguard was rubbing / pushing the front band.... I filed it down to be a "looser" fit, and that helped, but... then the support ribs inside the vented handguard were a issue... Lol.
I promptly put the Match prepped OEM back in place. That one has the "ribs" ground flush. So no extra barrel contact.
Precision went back to normal.
I still love that heavy beast. It has never once failed to feed or eject with CMI, those Taiwan mags and USGI mags.
Like a trusty tool, that rifle just works.