Try a science lab supply house...have varisous sizes of capped test tubes and plastic vials (along with some great squeeze bottles for your solvents...good bushes for nooks and creases).
Truth is, becasue we load by VOLUME...can use the graduated ones to measure the charge.
If you shoot cap-and-ball revolers, the test tube cleaning brushes are great...have bristles over the end, so it reaches to the very bottom of the chamber.
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Got any friends who are surgury techs, surgury nurses, or rad. techs?
Lot of procedures (like lumbar puncutures) come pre-packaged and disposable. The kits often have plastic fluid collection vials (with caps). Often they aren't used in the procedure but they cannot be sterialized for reuse, so are tossed.