Suppressors and Velocity Part II

We were able to round up four more firearms for testing with our Form 1 suppressor.  Here are the results.

Firearm 1
Custom Barreled Ruger 10/22 Takedown Model

Our Ruger Takedown had both the original 18.5 inch barrel and a custom 10″ barrel with a pinned shroud to bring it out to the NFA-mandated 16 inches.

This rifle used a standard production stainless steel barrel measuring 18.5 inches.  Data was shot using the original barrel unsuppressed to provide a velocity baseline. It averaged 1033 fps with the test ammunition.

Instead, a custom barrel provided by Cole Bender of Proof Research was used to compare velocities between the suppressed and unsuppressed barrel.  This custom barrel began life as a standard 16.5 inch Takedown Tactical 10/22.  It was then cut back to 10 inches and a shroud was pinned and welded into place.  The permanently attached shroud brought the overall length to 16.25 inches, making it compliant with NFA rules.  The rifle can be fired in this configuration, or the suppressor can be inserted into the shroud and screwed into place, making the overall length 18 inches.  The shorter barrel length helps lower velocity for quieter suppressed shooting and keeps the rifle from becoming unwieldy with the suppressor in place.

The pinned shroud allows a suppressor to be used without adding excess length.

Suppressor in place on the range.

The 10 inch custom barrel produced an average of 1005 fps.  The velocity of the suppressed barrel dropped to 993 fps.

Extreme Spread Suppressed: 57 fps
Extreme Spread Unsuppressed: 99 fps
SD Suppressed: 22.7 fps
SD Unsuppressed: 28.0 fps
Velocity Shift: 12 fps increase for the unsuppressed barrel (1.2% increase)

Firearm 2
Ruger 10/22 Charger

Ruger 10/22 Charger Pistol

This pistol uses a standard Ruger 10/22 action mated to a 10 inch barrel.  Because barrel lengths between the custom 10/22 rifle and the standard production Charger were similar, it made sense to expect related ballistic performance.  Instead, the Charger posted higher than expected velocities both with and without the suppressor.  The unsuppressed barrel produced an average velocity of 1031 fps and 1025 fps while using the suppressor.

Extreme Spread Suppressed: 44 fps
Extreme Spread Unsuppressed: 39 fps
SD Suppressed: 13.1 fps
SD Unsuppressed: 12.1 fps
Velocity Shift: 6 fps increase for the unsuppressed barrel (0.58% increase)

Firearm 3
Ruger American Rimfire Target

Ruger Rimfire Target

The Ruger Rimfire Target is built around a handsome 18 inch heavy barrel.   While a beautiful rifle, accuracy was only mediocre with the CCI Standard Velocity cartridges.  Accuracy with the suppressor was non-existent and the shot-to-shot sounds emitted from the suppressor varied noticeably.  It seems likely that the bullet was interacting with baffles poorly, although none of the baffles showed signs of a bullet strike when the suppressor dismantled for cleaning.  Velocity from the unsuppressed barrel averaged 1078 fps and 1066 fps suppressed.

Extreme Spread Suppressed: 39 fps
Extreme Spread Unsuppressed: 30 fps
SD Suppressed: 14.4 fps
SD Unsuppressed: 9.9 fps
Velocity Shift: 12 fps increase for the unsuppressed barrel (1.1% increase)

Firearm 4
Ruger SR22

Ruger SR22

Coming in at 3.5 inches, the SR22 used the shortest barrel in our testing.  Based on our experiences with the 4.4 inch barreled Ruger 22/45 Lite, there was some expectation that velocity would increase using the suppressed barrel.  There was an increase, but it was very slight.  The unsuppressed barrel produced 902 fps while the suppressed barrel averaged 907 fps.

Extreme Spread Suppressed: 24 fps
Extreme Spread Unsuppressed: 36 fps
SD Suppressed: 8.0 fps
SD Unsuppressed: 12.1 fps
Velocity Shift: 5 fps increase for the suppressed barrel (0.55% Increase)

What does it all Mean?
When we set out with this fun project it was just intended to answer a simple question: Do Suppressors Increase or Decrease Velocity?  We chose the .22LR for testing because we had a readily available suppressor and several firearms with threaded barrels at our disposal.

The commonly accepted answer among shooters is that suppressors increase velocity.  What we found (within a muddle of data) is an answer that is common in the ballistics world: NOT ALL THE TIME.

If you were to bet your friend that his Ruger Charger would shoot faster using your suppressor, you would be making a dangerous bet.  If the bet was that he would shoot one shot and then a second shot with the suppressor in place, the results, based on our data, is that either of you could win.  Using our data and comparing the strings two shots at a time would result in the suppressed Charger winning 4 out of ten times.

Even if the betting was reversed, and your friend used our data to prove that his Rimfire Target rifle shot faster without the suppressor, and the test was conducted using just two consecutive shots from our data, he would lose 40% of the time.

When the standard deviations are considered, the loss of a beer on either side seems as likely as a coin toss.

There are a couple of points within our testing format that we knew were limited.  The most obvious is sample size.  With much larger samples, the shot-to-shot variations so common to .22 LR cartridges would iron out and begin to show true trends in velocity.  But that type of testing is beyond the scope of this little experiment.

Going back to the people in that meeting a couple of weeks ago, it seems that those who suspected that a suppressor would do nothing to the velocity were correct.  There were increases and decreased between barrel lengths but none produced a significant velocity shift, with the exception of the first pistol tested.   The data for that pistol also based on the smallest number of test shots.  Of the next four firearms tested, two produced slightly more than 1% increases in velocity WITHOUT THE SUPPRESSOR. The other two split the difference with one increasing velocity by .5% with the suppressor in place and the other losing by the same margin.  This in itself is perhaps the most telling statistic.  Statistically it made no difference.

These answers are only true for this suppressor, using this ammunition, under these range conditions but they are some of the answers.  The answer at the end of the day for these .22 LR firearms was that adding a suppressor had no significant affect on velocity.  Some increased, some decreased, but the numbers were never significant enough to offer a definitive answer.  The lab, with their more sophisticated equipment and controls may tell a different story.