Matt recently comment on this post about the Australian AUG A4 (ADI Austeyr F88 A4):

To clear up “125″ issues and confusion the A3 varient is to be upgraded to allow the firing of GLA and underslung shot gun attachment with the trigger finger. There is much speculation on INF 2012 weapon systems and the steyr will look marketly different. What is concrete is that what changes happen to the weapons system the it must have the same range or better and must not be any heavier than current weight with modifications. There is a photo around of an ugly australian modified A3, this is not the new rifle and was a test bed system and was a demo only. The ADF rumour mill is leaning more to the AUG A4 design as now Australia owns the rights of all world wide styer production and also pattened designs from Austria.

I had not idea that the A4 existed. I did some Googling and found some photos in a brochure from ADI, the Australian arms and ammunition manufacturer. They may be the “test” A4 that Matt mentioned in Matt’s comment.

I think it’s a pretty ugly design. It looks like someone attacked an AUG with a hacksaw, screwdriver and a few picatinny rails. Especially in contrast to the AUG A3 (from steyr-arms.at):

Where is the grenade launcher trigger?

I would be surprised if the Australians upgrade their A1/A2 AUGs to use the M203 when the M320 will go into production later this year (according to Wikipedia).

M4 with M320