What gun is this? (Now with an answer!)

This is not a test - it's a genuine question on my part as I can't work it out.

Sticking with my Arctic Front theme, I've been looking at pics of Norwegian AFVs - in particular the NM135 as I'm trying to work out how to scratch build one (based on an S-Model M113 kit).  Here's a couple of pics for reference:

Whilst looking around I came across a nice Norwegian site Stormskadron 3 which has some terrific shots of NM135s and also some shots of mechanised infantry.  Again - great reference shots.

Looking through them I found one long arm in particular that I couldn't quite work out.

This chap has one next to him

The chap on the far left has one.

Maybe the chap in the front row, 3rd from the left has one.

If they are all the same gun, based on the bottom photo it might be an AG-3 with an underslung grenade launcher.  Maybe the chap in the middle photo has popped the breech open?

I've no idea - but before I start work on my Norwegians I'd love to know.  I do like how all their AG-3s have extendable butts.  Very cool and useful inside a cramped AFV.

So - let me know if you know!

**UPDATE**

I have now been reliably informed that my guess was correct and they are indeeed AG3 assault rifles with an undeslung HK79 40mm grenade launcher.  Just out of interest the last photo also has several chaps with HK MP5 sub-machineguns.

Thanks

Richard