' I experimented around by inserting different size pictures in a Word document, and found that the code below will loop through all the pictures and set them to a width of 340 if they exceed 340 (to convert 340 to inches, since this is in points -- divide by 72.
Public Sub Main()
Dim myPic As InlineShape
For Each myPic In ActiveDocument.InlineShapes
myPic.Select
x = myPic.Width
If x > 340 Then
myPic.Width = 340
End If
Next
End Sub