One of mine was in the recall S/N range...a new .58cal flint barrel they built for me back in the spring.
GM told me that they went to a new thread tapping process for nipple seats and vent liner seats, and discovered that the height of the threads may not be precisely as high as they sould be, with thread edges more rounded than as sharp as they should be...worried about possible blowout,
sent me a prepaid UPS call tag...probably replace the breech plug.