One interesting specialized version of the Steyr MPi-81 is this model, built for the Steyr/Saurer 4K 7FA armored personnel carrier. The vehicle could carry 8 infantrymen and their compartment had four firing ports fitted with MPi-81 SMGs. The changes required from the standard MPi-81 pattern were:

- A longer barrel to fit into the gun port
- An optical sight very much like that of the Steyr AUG
- Removal the front sling swivel
- Addition of a mounting bracket for a brass catching bag

These are very rare guns to find these days, and I’d like to thank Joschi Schuy for giving me access to his to film! Additional thanks to the Heeresgeschichtliches (Military History) Museum in Vienna for the photo of the IFV.