The MSAR rifle has a non-reciprocating charging handle, a last-round bolt-hold-open, 1:8 barrel rifling for better performance with a wider variety of 5.56 bullet weights. a number of additional sling points, a modified, improved trigger and an overall we

The STG-E4 appears to be made with the same features, having a reversible ejection port, simple take-down system, and using the same quick-change barrel system. One small cosmetic change is the option for more Picatinny rail sections for accessories.

One of the biggest change has to be the use of AR-15/M16/M4 magazines.

A number of additional sling points, a modified, improved trigger and an overall weight of half a pound less than the Steyr rifle.