hola un ejemplo muy sensillo con un minimo de 0 y un maximo de 100, despues si queres utilizar otros valores es pura matematicas
Option Explicit
Dim oPicProg As StdPicture
Private Sub Form_Load()
Set oPicProg = LoadPicture("C:\barra.gif")
DrawProgress Picture1, 50
End Sub
Private Sub DrawProgress(PicBox As PictureBox, ByVal Percent As Long)
PicBox.AutoRedraw = True
PicBox.ScaleMode = vbPixels
PicBox.Cls
If Percent > PicBox.ScaleWidth Then Percent = PicBox.ScaleWidth
If Percent > 0 Then
Percent = Percent * PicBox.ScaleWidth / 100
PicBox.PaintPicture oPicProg, 0, 0, Percent, PicBox.ScaleHeight
End If
PicBox.Refresh
End Sub