VB Grenade Question

[EODGUY]

Just picked up a VB practice grenade with the typical red top. Everything is present and on good shape except there is no cal. .22 rimfire round. Am I correct in assuming that the practice grenade did not have the rimfire installed? I do not have any information on the round that goes into that ;eve; of detail.
Also, can anyone identify the "SU" marking cast into the body? The "U" is hard to see in the photo.

 

[Eodtek]

The casting should be US for United States. Our original stocks were French in origin. The "rim fire" round is referred to in the manual as a "primer".

The Ordnance Committee declared it obsolete in 1923. The only pub I have is from 1917 and doesn't address a "Practice" version, just a dummy version. The photo you are showing appears to be the explosive version.

 

[Millsman]

The latest I've seen was a French example dated 1937.

 

[Eodtek]

Here is the US Pub on the VB Grenade.