the g36 sling mount point is kinda narrow. To get a magpul ms2 and ms3 to fit you need a carabeener or other clasp that will fit in the rear sling mount point on the body. Don't use the one on the stock. I wouldn't trust it. Also the one at the front might be too tight for some slings. I ended upbuying the magpul rail mounted sling loop for the front and using a screw clamp on the rear.
A 2 or 1 point would be better for a g36... a 3point is going to get in the way.