No, it's not that, but you're close.
What you need to do is:
policy-map METRO-10
class class-default
shape average 50000000
However, you might want to rename the policy to METRO-50 and you might want to change the bandwidth settings in the child policy, METRO-PRIVATE, to take advantage of the additional bandwidth.
You'll also probably should change the bandwidth setting, on the egress interface, to reflect the increased bandwidth too.
Lastly, I cannot say how a 4600 works, but on many other Cisco platforms, shapers, I believe, only account for L3 bandwidth, but providers often provide bandwidth as L2 bandwidth. If your shaper doesn't account for L2 overhead, I've found using a shaped value about 15% less usually accounts for average L2 overhead. (NB: insuring the shaper isn't allowing more bandwidth usage than available, is especially important when supporting VoIP. Also when when using QoS that supports VoIP, you might want to decrease the egress interface tx queue size.)
PS:
BTW, match IP prec 5 will also match IP DSCP EF.
