What shows in mainland Europe are open to hunters, not just gunwriters or gunshop owners?

...the IWA is only for trade visitors and not open for public. Look on the website for admission criteria. Maybe as a military you can get in.
There is in February the "Jagd & Hund" in Dortmund one of the biggest hunting show in Germany.
In Februar too is in Salzburg/ Austria (close by the german border) the "Hohe Jagd" as the biggest show in Austria.
In Dezember is in Hannover the "Pferd und Jagd" as biggest horses, hunting and fishing show in Europe.
There are many small local shows who advertise in the hunting magazins
Make your trip if possible not on the weekend. There are not so many people.

Waidmannsheil

Vogtlaender

Thanks good to know!

Add to the list HIT, hold in Vicenza (Italy) in mid February. You can fly Ryan Air to Treviso and then drive abou 50 miles to Vicenza.
The show is great, but the parking facilities are close to zero.

No parking?

Sounds like anything else I have ever done in Spain, Italy or Australia.

I'll pass on that one.

The biggest one in Germany is Jagd und Hund in Dortmund, it start 31-01-2017! I like this show very much!