Best primary for Factory/Kolkhoz?

So, I've just finished Intrusion, which was f*cking scary. I didn't have enough money for body armour or a lot of stims, and the AKM I was using with AP ammo was surprisingly weak against enemies there (had to use three rounds to finish a normal mimic commando, maybe that's normal, maybe not), so I made it out by the skin of my teeth. AKM got ruined, so I sold it along with all of the other stuff I scavenged, so now I have a nice 9.5k.

What should I prioritise getting? Should I get body armour and then purchase a weaker weapon, or a decent L4 primary and then get body armour later? I'm currently running with an M9 as my sidearm, which is suiting me well, maybe I should just use that for close quarters and buy a Mosin or something?