I think it rather was to be.

It looked very much like the second R 100 example here:
http://img.photobucket.com/albums/v432/Grzesio/21cm_BRs_R100-Model_SH.jpg
...but had six folding fins on the bare nozzle, looking very much like the R 4M ones. The whole rocket was to be 1825 mm long and have 600 mm fin span.
Anyway, I've found pretty interesting information on the R 100 BS evaluation in the USSR. The rocket was developed as the ABRS-220 there, but the Soviet version of the Brandschrapnell warhead was found to be completely ineffective - incendiary pellets were colliding in the air, splashing flaming contents all around - the view was impressive, but nothing more.
Regards
Grzesio