Here is my experience with the Panzer M4:
I bought one of the early import Panzer M4's back in January 2021. I was having problems with it right out of the box and sent it back for warranty work. I got it back without it being repaired and it was still having problems cycling shells, so I replaced the following parts:
70037 Benelli M4 Extractor
70036 Benelli M4 Extractor Pin
70038 Benelli Extractor Spring
70057 Benelli Cartridge Latch Spring
I purchased those parts from Midwest Gun Works in November 2021 for my Panzer M4. At that time, the total cost of those parts, including tax and shipping, was $45.86. My Panzer now runs 100% with ALL shells that I've tried including 1145 fps cheap birdshot and hot buckshot. I'm very happy with it, but I only have a few hundred shells through it. Also, my front sight post loosened itself up, so I think a little blue Loctite would keep that from happening again.
Border Dave