The SRSA1 is described as:

A bolt-action bullpup, compact for CQB.

You can pick this up west of central Mojocoyo, in the a cocaine hideout. The “Hidden Cocaine Cache” mission is nearby. The weapons case is in a tunnel under a hill.

I came at this from the main road to the south, and drove off the road on a motorcycle directly towards the weapons case icon and there was nothing. It’s under the hill! So I then moved towards the entrance and took a look. There are five… FIVE snipers on the hill overlooking the entrance to the cave under the hill. Take them out first. Then there are five more enemies inside and patrolling around, but there’s lots of cover for you to take them down one-by-one.

The SRSA1 scores very well on noise reduction, beaten only by the G28 (found in San Mateo), however I find its description kind of ridiculous – this gun does score top in its class for handling, but it doesn’t matter how compact this rifle is, you can’t use it for CQB, because it fires far too slowly. Speaking of which, you better not miss your shot, or your target will be behind cover before you can send a second round their way.

It uses the high powered .338 round, so it has a 5 round standard magazine, and a 10 round extended mag can be found in Remanzo.