What does the SA stand for?

Caleb, SA is the acronym for 'Short Action' in this description. This is a remington model 700 short action 308 bolt face. It is stainless steel with an externally adjustable X Mark Pro trigger.

Short action 243,260,7mm08,308,6.5 creed

SA= Short action cartridges based off the .308 are short actions off the 30-06 (like the 270) are long action it has to do with the length of the case the ballistics of the 308 and 30-06 are almost the same but the 30-06 is a longer cartridge

Caleb. Short Action Sir which the 308 is a short action cartridge requiring a short action bolt. A 30 06 would be a Long Action LA.