I remember hearing about the finish problem but I must have missed the second issue that held things up.If I remember right, Shield had two different snafu's with Checkmate (I believe that's who's making them). Finish was bad once and something else. It was two big set backs for them.
I did read where Brian at Shield said he was giving no dates or possible dates for Glock 43 mags. Just that they were "in the works". Even if they can do a 8-9-10 round flush fit mag for the 43, people are going to go nuts for them.