This is a standard 9x19 mm P7M13.

The P7 pistols came in the calibers 9x19 mm (PSP, P7M8, P7M13), .40 SW (P7M10) and also a few prototypes in .45 ACP were made (P7M7), as well as the P7K3 which could be converted between calibers 9mm kurz, 7.65 and .22 LR.

Additional info on the various P7 models can be found at HKPRO and HKP7.com.