Rimless cartridge M27

These two flare type rounds marked M27 were found in the cardboard two part tube pictured above. The cartridges are dated 1945. From other research, it appears they were used to simulate the high burst of artillary projectiles. Maybe antiaircraft? Does anyone know what sort of gun they were fired from? Because the casings have no rims it’s something of a mystery.

Looks like the family of flares & signals for the AN-M8 pyrotechnic signal pistol, but which was meant for the ground-projector version; M1A1, where you would drop it in like a mortar, instead of being held in a pistol chamber and needing to have a rim. A link here describes it and there is a diagram at the top of page 33 showing it: http://books.google.com/books?id=YDQYAAAAYAAJ&pg=PA31&lpg=PA31&dq=ground+projector+m1a1+m27+signal&source=bl&ots=KAbjqsCqce&sig=VxBpROaGEffE0as3xjsGXqTAE8w&hl=en&sa=X&ei=N0kwU8e8BsXR2AXawoCAAQ&ved=0CCUQ6AEwAA#v=onepage&q=ground%20projector%20m1a1%20m27%20signal&f=false

Greg, this is a ground signal used to simulate the high burst of artillery shells and it was fired from the M1A1 (spiked) and M4 ground projectors. It is loaded with 2 oz. of black powder and 0.2 oz. of aluminum.

M4 Projector:

Thank you. It’s nice to know how these things were used. Are these things particularly collectable?