Understanding policing on catalyst

Hello, all. In previous post I wrote example of policy'ng on catalyst MLR 4900 series.  Today,I tested how work's policyng, and i have a problem:
Config policy-map:
policy-map POLICY-NAME class SC-1245309
police 10485760 bps 1966080 byte conform-action transmit exceed-action drop
!
class-map match-any SC-1245309
match access-group name SC-1245309
!
ip access-list extended SC-1245309
 permit ip host 10.10.10.10 any
 permit ip any host 10.10.10.10



 I began ping -f 10.10.10.10, and monitor traffic on port, and I got result:

 TxSpeed = 1600163*8/(1024*1024)=12,20Mbps.....But in config i wrote police 10485760 bps.(10 Mbps) Let's understand why we see this result......
If I  run command ping -f -s 1000 10.10.10.10 I see result:

 

Now we see TxSpeed = 1341781*8/(1024*1024)=10,23 Mbps. This result better than previos. We have this result becaues when we strat ping with param: -f, we send many packets whith default size (we have many L2 headers. Cisco match only L3 trafffic), and if we start ping with -s 1000 parametr (size of one packet), we have result 10 Mbps,   because at this example we have less L2 headers. 

P.s. sorry for my bad english)))