The Eprouvette: Old School Quality Control

In an era long before mechanical precision, quality control was much less of an exact science than it is today. Without robots, computer programs, etc, it was up to people to do the best they could in ensuring that a product’s quality was consistent, time after time.

Gunpowder was just one of the many items that needed to be made to the same exacting specifications from batch to batch. If quality control was lacking and a sub-par batch made it out the door, it might be too weak and not ignite properly. Conversely, it might be too strong and cause a catastrophic failure in the firearm shooting it. Either result is bad for business.

This is where the eprouvette comes into play. Its operation is incredibly simple, but it was also incredibly effective. A charge of powder was loaded into the barrel and the flashpan. When the flint ignited the powder charge, the steel cover on the end of the barrel was pushed away from the muzzle by the pressure of the explosion. This moved a numbered gear to a certain notch. The number at said notch was noted and the powder mixture was deemed correct, weak, or strong.

Repeated testing ensured that each batch of powder met requirements. The method wasn’t perfect, but it worked.

(Eprouvette courtesy of NRA Museums)

Logan Metesh is a firearms historian and consultant who runs High Caliber History LLC. Click here for a free 3-page download with tips about caring for your antique and collectible firearms.


  1. avatar Jeremy in AL says:

    That’s really cool. More please

    1. avatar Sam I Amq says:


    2. avatar dlj95118 (soon to be 83544 - house closed!) says:


    3. avatar michael in ak says:


      Very interesting. What other methods were used to standardize gunpowder?

      1. avatar Geoff PR says:

        There is a modern version that uses a PVC ‘bird’ sleeved over a copper pipe to ‘launch’ the ‘bird’ straight up. Flight time or ‘bird’ altitude is the relative powder strength indicator :

        Feel free to improve on the design….

  2. avatar Owen says:

    I saw a similar test device on a tour of the black powder factory site called the DuPont Powder Works / Hagley Museum. You put powder in it and the explosion spun a wheel to a certain mark to show the power. They have other cool stuff there to see if you are ever in Delaware. The water turbine powered, belt driven, machine shop is really cool.

    1. avatar Philip Cathell says:

      +1. I came here to mention the Hagley also!

      The other standard was a mortar shot thing which had to launch a cannonball at least a football field length or so?

  3. avatar PeterK says:

    Huh. Ingenius.

  4. avatar Bloving says:

    Notice something else: the simple stamped decoration on this tool. Does nothing at all to improve its performance or ease of use… it simply pleased the craftsman who made it to do so.
    I’m sure there are examples of modern manufacturers taking such pride in their product that they will include small gestures of vanity in their products at no extra charge but sometimes we have a hard time thinking of them.

  5. avatar Gralnok says:

    Nifty little contraption!

  6. avatar Ogre says:

    You can purchase a reproduction eprouvette at Dixie Gun Works and test your own powder, thank you very much!

    1. avatar Geoff PR says:

      Good to know, thanks!

    2. avatar Geoff PR says:

      Where on their web page is this eprouvette?

      A search for eprouvette returns “nothing found”…

  7. avatar Geoff PR says:

    Here’s one ‘in action’…

  8. avatar The Rookie says:

    Very clever!

  9. avatar billy-bob says:

    Is it just me or does it look like a flintlock pizza cutter?

    1. avatar BLoving says:

      If it was one – it would be on order to my house already.

  10. avatar ironicatbest says:

    Hogg wash, that is nothing more than an evil black as salt rifle in disguise. I saw one of these at a Hide Behind A Door Cower In Fear, seminoles

  11. avatar little horn says:

    neat. i thought it was a steam punk pizza cutter

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