I have the Armo 2cm Flak 38 barrel #35708 (only one barrel, not 4). It is very nicely done. I also have the Jordi Rubio barrel, and it is not as nice.
I've got a few 1/72 scale Armo barrels as well and I am generally impressed with the quality. My largest Armo item is the GAZ-67B post war conversion for the Tamiya Russian Jeep. Very nice resin/PE set for that old kit.