They shoot excellent in my setup which is an 870 youth compact with a JEBs .555.
Mine shoots a pretty hot core (consistent 410 to 425 pellets in 10inch at 40), which could probably be even tighter if I opened up the choke to a .562, .565 or .570.
If these shells don't shoot in your setup, it is likely just a matter of altering the choke to put the pellets where you want them. To the best of my understanding, they are the only 2oz 20 gauge TSS load on the market. Pretty nice folks to speak with as well.