Agreed. Only way I found out was I talked to Carlson's at NWTF in Nashville last year. I had thought they made the choke since they developed the Longbeard XR load. They told me that Briley made it for Winchester. I bought a SX3 Longbeard last year. I love the gun. It's actually for my wife. She loves it also. I can tell you the choke tube that came in it sucks for patterning all loads I ran through it compared to the 5 other chokes I tested with. It finished dead last with every load and had lots of gaps in the pattern.
You are correct the only writing on the tube is Winchester Longbeard something.
The gun owner in the pic said the choke was screwed in tight fwiw. I thought it could be that or using 4 shot in a choke too tight. Of course the keyboard warriors jumped on that saying they use 000 buckshot through their extended super full choke tubes as well as slugs. Some folks you just can't help.