Q:  What is the P7-A10 XM9 Prototype made for 1980 USA Service Pistol Trials

A:  The precursor to the P7-M13 that was ultimately submitted for the pistol trials was a prototype of the P7 that utilized a single stack 10 round magazine.  There were reportedly 33 such units produced for the early trials and testing.  Here's a fine example that was for sale in Germany in December of 2010.

 

Description from the Ad:

Pistol - H & K P7-A10 XM9

* Cal. Cal. 9mm Para 9mm Para
* Condition 2
* Burnishing 2-3
* Running a mirror finish
* Self-loading pistol with gas braked mass closure and unique hand clamping system (translation from German not totally accurate - should read gas delayed, unique grip cocking)
* Spare Magazine
* 10 shot version with extended magazine
* Sent to USA for testing
* original packaging
* original manual
* original P7-XM9 grips
* Only 33 pieces produced!
* S / N range: 27841-27873
* S/N: 27867
 

 
  Other pics of XM 9 Prototypes shown below.  This one was 27859 which was in the S/N range give above.