I have never used a set of 10-ga. to 12-ga. Chambermates, but I do have a set of 28-ga. to .410 Chambermates that have never failed. They stay in the chamber and eject the spent hulls reliably--what more could one ask for?

Here's a pic of my Po' Man's Parker 28/.410 bi-gauge set. It's a 28-ga. Parker Reproduction 2-bbl set with a set of 28/.410 Chambermates.