I used a lot of small samples. I was able to check the mortises with the sample to make sure the angle was correct.
The muntin tenons are about 1/2" in length.
The muntin that intersects the corners does not have the full tenon on it. I didn't want to weaken the main mortise and tenon joint by cutting into it any more than I had to.
Everything fitted and sash is ready for the finishing touches.