Want to know if your 40mm GL is an RIF? LOOK NO FURTHER.
If it ticks the following boxes:
-Is the same size as a real 40mm launcher could reasonably be
-Has a pistol grip or other free-hand grip
-Also has a trigger
-Is in a realistic colour
Then congratulations, it's an RIF!
If however, it resembles a tube with a trigger or button on the end, it's just a tube with a trigger or button on the end.