Scavenger mod for ITR is pretty interesting. Early game you've got so much shit it's easy as hell. Then you peek into factory and face armoured enemies without any AP or +P. Not being able to get what you need, but still being flush with items, is very different to how ITR usually goes. I've found hit and run tactics surprisingly effective. Getting inside, popping the rift, then running back out to plink at stragglers is the only way I can think of to get through this part. I found a full length wooden PPSh and three drum mags for it but even fully loaded with +P it's a real challenge to drop anything armoured before they return fire. My SKS only has 10 round mags right now so it's not very useful either. Gotta have a really good rummage around and see if I can find a crate of AP ammo and load up whatever weapon shoots it before I try to go back into the factory bombing mission. Ran in and dropped the rift in the locker room but didn't get any kills upstairs. Still a successful visit as the shortcut from Route is more or less clear now.
Last time I did this mission vanilla I did the whole thing with an AK47 and about eight mags of AP ammo.