Listen for that ring you mentioned. How do you pick it out over the forge noise and hammer strikes? I've had times where I thought I heard it right but still got cold shuts. Were you using mild steel or something with more carbon? Also, did you change how you held the cross peen for those solid blows? Like, more angle or less force on the follow-through? Just trying to nail down the details so I can try it myself.

Cold butter is important, but don't forget the water and even your hands. If everything stays cold, the butter bits stay solid until baking, which makes steam and flaky layers. I grate frozen butter into the flour sometimes for even mixing. Overworking the dough with warm hands can melt the butter too soon.