No i dont think it is, by how there isnt the permanent hendsolt scope and it seems like there was no welding done. I say its just a customized HK91 i could be wrong though. There is also the front sight on the end.
heres what i can tell you off hand... take it for what its worth
1) the sight mount is FIXED not the standard clamp mount found on an HK9-serie.
2)it has both the standard HK hood in the front and a drum in the back... from here it looks to me like an MSG90.
3) non of the furniture counts, since ALL of it can be aftermarket.
4) it is possible that this is an MSG90 since the DoD uses them with the drum rearsight and the hooded front sight.
5) THE PIC SUX
If I had to guess it could be a Springfield SAR-8 Target. Springfield made a Target model that looked just like the PSG-1. The target model still had iron sights, PSG-1 don't (that I have seen). The target model had a smooth heavy barrel with no break, the same forearm and iron sights.
I have never heard of it before, but all it needs is a rear stock change!!
"HK SR9, is the PC (politically correct) Version of the HK91, it has a thumbhole Buttstock, no Flash Suppressor and comes with a 5-round Magazine and an improved Recoil Buffer System, it fires the .308 nato round." - from the above website
ill have to agree with Mel and Caver:
since its got iron sights.... theres pretty much NO way it would be a real PSG1. the MSG 90 also had fixed sights (the DoD ones) but they had sights similar to the HK21 machinegun....