Nigel Just Nigel

Apologies if this is in the wrong topic thread, (new user).

Recently purchased, but the YouTube reviews I saw said there was rubber seals/stoppers/ things that prevented bb's from just falling out once loaded. I found sometimes they do, and not always the same barrel, and that's in a calm test environment, not running and shaking and rattling across an airsoft field. Could someone confirm weather or not it should have little rubber things in the small holes in the barrels, and if it should, where can I get some if they know or have had this problem themselves. I hoping I don't have to bodge a fix with tiny lumps of blu-tac.