The barrel consists of a black plastic tube with similar white lids top and bottom. The challenge is to leave the bottom securely in place at all times, because if it separates even a little, some shot intrudes into the gap and prevents it from being re-seated.

You then have to empty the whole thing, clear the obstruction and re-fill from scratch.

If I were buying again, I would definitely go for the aluminium lid with a venting facility. Dennis.