Artillery primers based on 7.62x51mm cartridges

I came across the following cartridge at SLICS. I believe that its from an early 1980’s ARDEC (Picatinny Arsenal) development project for a primer for the lightweight 155mm Howitzer. The headstamp is (+) LC 79. The purpose of the split bullet seems obvious, but why the four holes in the case neck?

Can anyone shed more light on this and earlier research carried out at Frankford Arsenal on a XM119 universal artillery primer that used a 7.62x51mm grenade launching blank?