Ported barrel FPS drop data

Hi y’all, Lee here with some information on a frequent question we get a lot here at Norsso. Most of our customers are curious about our barrel options as well as our GEO port versions and what the differences are. Three of the biggest questions we get asked are about:

-          Recoil reduction

-          Velocity loss

-          Accuracy/Precision

We’ve been spending some R&D time at the range and were able to put aside some data for the velocity question. We’ll get to the other two later but for now, we have some test data to share on velocity.

In case you’re new to the term or its application in firearms, when we refer to (muzzle) velocity, we’re talking about the measurement of speed after the bullet leaves the barrel. This measurement has many uses, e.g. in calculating the trajectory, or the amount of energy the round has on impact. The uses of these values vary across the firearms industry, but the definition of velocity remains the same. You’ll see the acronym FPS on your ammo boxes. This is their rated velocity and stands for Feet Per Second.

The most accessible way to measure a bullet’s velocity is a Ballistic Chronograph. Not the wristwatch type, but the ones that either use an optical gate or radar. For our testing, we use the Xero C1 Pro Chronograph. The C1 Pro can measure projectile speeds from 100fps to 5,000 fps and even tailors the readings to the grain weight of the bullet.

To test the difference between the standard and ported barrel sets, we’ve ran each setup on the same frame with factory internals and an optic. We chose 3 different ammunitions to establish a variety of velocity baselines and shot 5 rounds through each combination to establish an average velocity. Below is the data. The heading shows which firearm platform the test was conducted on.

Some quick takeaways of the data are that the FPS drop from a standard to a ported may not be as much as you think. For most ammunitions with our ported barrel, you’re seeing a velocity drop of less than 5%. Also, the longer barrels seem to have slightly less drop than their shorter counterparts. Nonetheless, here’s your data for those curious about the amount of velocity loss when switching to a ported barrel. Note that these numbers were determined from our barrel sets per platform. We’ve done prototyping with many different porting patterns (inline vs diagonal), adjusting the amount of gas flow area (how big the ports are), and the timing of the ports (the distance from the chamber) and we’ve found that our current GEO port pattern offers a very practical balance. We plan to conduct more testing with our products to get some concrete details.

A taste of precision data: We have some more to learn about how to set up a more optimized test setup for accuracy and precision but we did put our best setup to the test on the rest. We did a 7 round grouping with SIG VCrown Competition grade ammo in our P320 Full size 4.7” standard bull barrel and here’s the grouping at 25 yards. We didn’t re-zero the dot so the grouping was off-center but we’re happy with the results.

-          Lee