Thursday, July 4, 2013

22 WMR Denim and Gel Tests from the NAA Wasp Mini Revolver

This is a second article to go along with the 22 LR testing documented HERE.  The catalyst for the comparison test was the recent acquisition of a North American Arms mini revolver with both 22 LR and 22 WMR cylinders.

Test Pistol:

Test Protocol:
Step 1)  Measure and record temperature and relative humidity.
Step 2)  Run a 5 shot velocity average over a ProChrono Digital Chronograph at a distance of 8 feet.
Step 3)  Run first bare gel test shot into a block of Clear Ballistics Gel that is calibrated to 10% Ordnance Gel density.  Shot distance is 8 feet.
Step 4)  Run second test shot through 4 layers of 14 oz. per yard heavy cotton denim.  Shot distance is 8 feet.
Step 5)  Run a 600 fps calibration test bb shot into the Clear Ballistics gel block and record penetration depth.

Test Results:

Video Documentation of the Entire Tests from Range to Bullet Recovery:

My Thoughts on These Tests:

The CCI 22 WMR Maxi-Mag generated about 100 fps more velocity than the previously tested 22 LR Mini-Mag.  The additional velocity allowed the bullet to penetrate deeper, but wasn't fast enough to cause bullet upset and expansion.  I saw no evidence of expansion with either bullet recovered from this test.  In the video, I mentioned the bullets were under published weight and had an angled bullet base.  I thought I would try to pull a bullet from an unfired case, but that's an inherently dangerous process due to the highly sensitive rimfire primer compound in the base of the brass case.  As it turns out, pulling the bullet wasn't necessary.

The June 2013 issue of American Rifleman features an excellent article from Richard Mann about the use of 22 Magnum as a self-defense load.  The online version of the article referenced here doesn't have all the pictures that the print version does, but in the printed article the recovered CCI Maxi-Mag HP pictured looks exactly like my two recovered bullets shown in the pictures above.  I have to assume that CCI shapes these bullets this way intentionally.

Having previously tested Critical Defense loads in other calibers, I had built up high expectations for the Hornday Critical Defense 22 WMR.  Unfortunately, the test pistol and this load were not made for each other.  The first indication of trouble came during velocity testing when evidence of key-holing was visible on the target.  If you know what key-holing is and why it happens, you can skip the next paragraph.

Key-holing happens when a bullet leaves the barrel without sufficient spin to stabilize the bullet in flight.  The unstable bullet will tumble as it travels through the air.  If key-holing is severe, the bullet impacts the target and leaves a long, key hole shaped, hole in the target instead of the typical round hole you see when the nose of the bullet impacts the target.  Excuse the over-exposed image below but I had to boost the brightness to get the white background to show through the bullet holes.  The 5 shot group on the left was shot with the Hornady Critical Defense.  The 5 shot group on the right was shot with the CCI Maxi-Mag.  You can clearly see the difference in how the bullets impacted the target.   

The Critical Defense also caused cylinder bind with my revolver that rendered the revolver inoperable by the 4th shot.  I had to clear the spent brass in order to complete the 5 shot velocity test.  I failed to recover my spent brass so I have no idea why the Critical Defense is the only load that has caused this condition in my revolver.  I'll have to do some additional testing to ascertain the root cause of the problem.

On the plus side, the Critical Defense did show some expansion with the bare gel shot and velocity was higher than the published specification from the test barrel length.

Pick or Pan:
While we didn't see expansion from the CCI Maxi-Mag, it did perform well.  This load is velocity starved with the short barrel used for this test so perhaps a lighter bullet would perform better with in this revolver.

The Hornady Critical Defense bullet was simply too long and heavy to be stabilized by the short barrel test revolver.  Further issues with cylinder bind eliminate this load from consideration as carry ammunition.

Disclaimer....This test should not be considered an endorsement or recommendation for the product(s) tested.  All tests represent actual performance in ballistics testing media.  Terminal performance in all other media will show different results.  It is up to each individual to make their own personal decision on which specific ammunition to use for their needs.  It's also critically important to test any ammo in YOUR SPECIFIC FIREARM before relying on it for any purpose.

Ammunition labeled as +P or +P+ should only be used in firearms that have been certified by the manufacturer as safe for the additional pressures generated by these ammunition types.


  1. I like your test better than Richard Manns'. He never said if the the bullets tumbled in the block. Also he didn't use the denim protocol.
    Great test. Thanks for doing it, there is not a lot of rim-fire gel test data from a snub available.

  2. So to ask the obvious, would you go with the Magnum or stick with the .22LR?

    1. I'd like to try the Gold Dot and Winchester PDX 22 WMR loads before pulling the plug on using magnum ammo "all the time" in this revolver. Another thought is to use 22 LR in the Spring/Summer and switch to magnum for Fall/Winter when the heavy clothing comes out.

      I hope to do more 22 WMR testing as ammunition comes back into the marketplace and prices return to reasonable levels.

  3. I also noticed cylinder binding from Hornady Critical Defense 22WMR in my NAA Pug. No such problems from other loads.