Previous Post
Next Post

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.

Previous Post
Next Post


  1. 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. 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?

  2. 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.

  3. 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


Please enter your comment!
Please enter your name here