Unidentified Disk, looking for some help.

[Remark]

I recently picked up this disk, but I have not been able to identify it.  It is JP or PJ over a crossed rifle and quill.

 

On a side note I really like the screw on nut since it is really unique to what I have seen before.

 

Scipio's the Collar Disk Story has it on pages 198-199 #30, but has it unidentified.

 

I cannot find it in LaFrambroise's books or in Emerson's Encyclopedia under Clerks, Service Schools, Service Corps or ROTC.

 

If anyone knows what it is please let me know.

 

Thanks!