From the Buffalo Bill Center of the West, McCracken Research Library digital collection, WRA Co. drawing collection here is a drawings of the V.B. Rifle Grenade; Mark 1, U.S. Ord. Dept. dated 1918.
Included in the pdf below is a screen shot of the drawing in its entirety and then screen shots of enlarged sections of the drawings to provide better detail.
Note the drawing includes details of the UMC Co. primer used to ignite the grenade fuze.