Actually, the tubes are made in two pieces, the main body and a little cap glued in the end to close it off. The cap tends to blow off on all the ones I've seen. These tubes could have been made differently - I suspect they were intentional in their design. We still have a lot of people around with S420's and E420 that are still rolling the M119 engine (though I still like the M113 better - near bullet-proof).