Tuesday, October 16, 2012

Underwood Ammo 9mm +P+ 115 GDJHP Clear Gel Ballistics Test


A few weeks ago I was catching up on old posts over at the Boberg Forum and noticed that Arne Boberg had posted that Underwood Ammo 9mm +P+ 115 Grain GDJHP ammo was safe to use in the XR9-S.  He had done the testing and did not find the ammo caused any strain or damage to the XR9 platform.  I needed some 125 grain .357 Magnum ammo so I put my first order in with Underwood since they claimed to manufacture their ammo with quality components and their prices were reasonable.  Secretly, I also wanted to see just how fast this 1400 fps 9mm load would go from my Boberg pocket 9mm so I also added a box of that to my order.

*** Additional Warning ***  +P+ ammunition is loaded to much higher pressures than standard ammunition.  Use this ammo sparingly, and only in firearms that the firearm manufacturer specifically states are safe for use with +P+ ammunition.  

I really don't know much about Underwood Ammo other than it seems to be the posted about frequently around the internet forums and has gained a very good reputation with folks.  It's made in the US and the 10mm fans can't seem to get enough of Underwood Ammo.  When I was searching around I found that tnoutdoors9 had been testing some of the Underwood Ammo and doing some excellent videos.  Unfortunately, I found nothing about the performance of this 9mm load from a shorter barrel length.   
Pistol Specs:
Boberg XR9-S with 3.35" barrel

Testing Protocol:
My testing process is pretty simple.  I take one shot at the end of a Clear Ballistics Gel block.  I take the shot from 8 feet away and impact velocity is measured 2 inches away from the block.  Clear Ballistics Gel is calibrated to 10% ballistics gel density.  I shoot the block at the range and then bring it home to analyze the block and recover the bullets.  Immediately prior to the terminal test, I shoot a five shot velocity and point of impact test string from 8 feet over a Competition Electronics ProChrono Digital chronograph. 
As my experience with the Clear Ballistics Gel product increases, I'm starting to better understand how to read the blocks and capture more of the data that is visible in the blocks.  You may have noticed I added two new data points to the test recap data sheet.  Those points are a measurement of the maximum stretch cavity height and also the penetration depth when the maximum stretch cavity was measured.  These new data points may provide additional comparison points between various bullet types and loadings as we collect more of this data over time.  The video below documents my entire test from range testing to bullet recovery.

My Thoughts
Since my primary testing focus has been on the shorter barrel lengths, I've never seen velocity and energy numbers like these in my previous testing.  It was very interesting to see the differences in the test block and recovered bullet when you drive speeds above 1300 fps.  That's an incredible amount of energy hitting the test block and also a strain on the bullet.  The Gold Dot bullet did well, but was stressed in ways I've never seen previously.  You may have noticed the absence of the trademarked Gold Dot in the center of the recovered bullet.  You can also see some copper jacket peeking through the lead core on some of the expanded petals.  These conditions may have been caused by lead "flowing" around the bullet core.  Also, I have never seen the Gold Dot petals expand to the point of wrapping under the bullet base.  Even with the additional stress on the bullet, the recovered weight was spot on with expectation.

Since we used a short 3.35" barrel in this test, it was unreasonable to expect 1400 fps velocity.  I was pleased that we lost less than 100 fps from the manufacturer published velocity specification.  

The high speed video for this test turned out well so I had to grab a still frame showing the "dynamic entry" into the block.

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. Very nice! Subscribed to you on YouTube (intercooler2). Are you taking ammo donations?

  2. Thanks for subscribing. I do take occasional ammo donations and there is a second tab at the top of the blog with instructions on how anyone can help fund more research if they so desire. Thanks for asking!

  3. Looks very good. How does it perform through four layers of denim?