The struggle is real.
I've had an open PO for GSG-522 Barrels (and 1911 barrels. and firefly barrels. and slides for both) on order with GSG since February and have thus far received zero this year. That Feb PO replaced an August 2019 PO for the same.
So, in regards to the GSG-5/522/16 barrels, here's some info:
After GSG's majority shares were sold to the L&O group (who also owns Sig, Mauser, Blaser, Diana Airguns and several other businesses) GSG's in house manufacturing was scaled down to pretty much just assembly. All or most of the machines (not sure what they have, I haven't gotten to tour the factory in many years now) were removed and parts supply was farmed out to other businesses. With that, GSG stopped having produced any parts that were not compatible with the newer GSG-16. One of the biggest parts to drop off was a barrel for any GSG-5 or 522 that had metal receivers. That includes:
GSG-5
GSG-5P
GSG-5PK
GSG-5 Limited Edition (2009)
GSG-5SD
GSG-522 w/ Metal Receivers
GSG-522P
GSG-522PK
GSG-522SD w/ Metal Receivers
When GSG introduced the "light weight" version with Polymer receivers at the end of 2010, the design of the receivers changed the breech block on the end of the barrel, so barrels for light weights are not compatible for guns with metal receivers. When we attempted to order more standard weight barrels earlier this year, GSG told us they no longer are producing them. So, the only barrels they will still be providing are for the polymer receiver 522s (which were only the carbines) and its the same bbl for the 16.
The other issue they have s that in Germany, barrels (and slides) are serialized items that require all the standard stuff that shipping a gun does. So, there's additional licensing etc involved for them to get them to us. I do not know if the parts like the guns are required to be proof tested by the government like the guns are, which would add in an additional hurdle. Each firearm, prior to being approved for export, has to actually be fired by a government official who then has to apply the proof stamp on each gun. If each barrel has to go through the same thing, I could see that being a giant pain in the ass but still.
We continue to push them to get us what we need but man, its been a tough road with a steep hill.