The repo grenade tubes as good as they look are a hair smaller in diameter than a real WWII M41 tube...a real one being about .86 and robs being about .76 and the black part of the tube on a real can being about .11 and the repo being about .06. the center cardboard tube on both are about the same at about .11
In the photo below the two repo cans are to the left. the other photo shows a real lid with Robs lid under it.
Thanks Dirt detective, this will make it easier to ID the replica cans. I will now have to check mine with this new info.