Unknown rifle grenade

[lilfry14]

Can anyone identify this rifle grenade?I assume it's a prototype/experimental. Is it possible to get a year based on the stenciling?

 

Stenciled PA-E8-396 

Loaded 8-??

 

PA is possibly Picatinny Arsenal?

[ordnance]

I can't provide a positive ID but it's definitely a U.S. experimental from the 1950s or early 1960s.  The PA-E stands for Picatinny Arsenal-Experimental.  Beyond that, I've got nuthin'.  I was tempted when it came up for auction but decided I didn't need to own it that bad.  Really neat piece, though.