All I see is their two-point sling wrapped around the buttstock. I don’t see any evidence of a buttstock mag pouch or readi-mag or anything like it. Doesn’t mean they don’t have any magazines handy, but I’m not sure where they are.
Of the picture of the 4 girls the one on the far left has a mag taped to her pistol grip, look close you will see it. the others most likely have them on the other side of the gun or maybe on their person. Now, look at the picture of the 3 girls(different group) their mags are readily visible. All of them who carry weapons carry ammo, would be senseless not too.