RSI Pressure Trace II Firearm Chamber Pressure System

RSI Pressure Trace II Firearm Chamber Pressure System

If you’re one of my regular readers, chances are you already know I do a lot of custom shotshell development.  In this article I’m going to introduce you to the Pressure Trace II, one of the tools I use to analyze my ammunition and determine chamber pressure.  This is extremely valuable to me in that it not only helps to establish whether a round is safe to use, but also how changing components, shot column height, or even the style of crimp can alter the pressure and performance of a shell.


Let’s begin by taking a look at the hardware. The unit itself is actually built right into a Pelican case.  This is fantastic as these things are built like tanks, and will provide a very reliable waterproof and shockproof housing which is important, as this thing isn’t cheap.

Inside you’ll find a strain gauge cable as well as a small extension which we’ll talk more about in a bit.  The construction of this tool is just incredible.  The top plate is brushed metal, the LED’s are large and bright, and the controls are clear and well labeled.  It’s obvious that the folks at RSI take great pride in their work, and that’s reflected in the craftsmanship.

In addition to the device and cables, this system also comes with a strain gauge.  Every time a firearm is discharged, the barrel momentarily expands in reaction to the pressure, then contracts back to it’s original diameter.  When properly mounted above the chamber, this tiny sensor will measure and record those changes, allowing the included software to calculate the pressure within.


Connecting the system is a piece of cake.  After affixing the strain gauge to the firearm being tested using the included bonding agent, the operator attaches the included extension cable to the connector.  This just gives you a bit more slack when using the firearm, to help avoid loosening or interfering with the gauge.

Next the user connects the data cable in the same manner.  With that done, plug the other end of the data cable into the pressure trace II, and secure it in place.

In terms of hardware, we’re now ready to go.  As the Pressure Trace II’s computer interface is wireless, connecting it to my laptop is as easy as turning on the Bluetooth adapter, and starting the program.


In order for the system to render accurate calculations, it needs to know about the barrel of your gun.  As you’ll see in the video above, I’ve entered all the pertinent information including the outside and inside diameter’s of the barrel and chamber, and the details of my verification load– basically a load with a known pressure value used for comparison.


With the system connected and configured, measuring chamber pressure is a breeze.  We simply click the ‘Shoot’ button and proceed to fire.  With each shot the system automatically records and graphs the chamber pressure, as well as other information like the ambient temperature and atmospheric pressure.  If something goes wrong, for example the system mistakenly interprets closing the action as a shot, you simply select and delete the erroneous reading and you’re back in business.

As the Pressure Trace II system also supports a chronograph, you can either connect a supported model directly, or manually enter data from your own after the fact.  One of the great things about this tool is you can do all your shooting during the day, then pack up and analyze the actual data from the comfort of your own home.  Every test profile is saved and ready for you to review and compare.


I can’t begin to tell you how many questions this system has answered for me; everything from how fold crimps compare to roll crimps in 12G pumpkinballs, to whether or not Mica wadslick actually reduces barrel pressure.  It’s taken my reloading and custom load development to a whole new level that simply would not have been possible without it.

I can’t say enough good things about the Pressure Trace II.  If you’re interested in learning more about it or purchasing one yourself, you can find the manufacturer’s website here.

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