A verb appearing as G. rag- “break asunder, burst” in the Gnomish Lexicon of the 1910s (GL/64), perhaps based on the early root ᴱ√RAKA “pile up”, though the meaning doesn’t match (QL/78).

Neo-Sindarin: The Quenya verb Q. rac- “to break” appears in Tolkien’s writings of the 1960s (MC/223), so I think this Gnomish verb can be salvaged as ᴺS. rag- “to break (asunder), burst”. For example, Fiona Jallings used rag- for “break” in her A Fan’s Guide to Neo-Sindarin (FGNS).