Saturday, July 7, 2012

New CORBON .32 Auto Denim and Gel Ballistics Test


A new Corbon 32 Auto loading started showing up in retailers like Cabelas in the last few months.  I had noticed that Corbon updated their packaging when I got my last box of .380 ammo, but the word spread around the KelTec and Seecamp boards that the new 32 load appeared to be loaded with the Speer Gold Dot hollow point bullet and not the rounded hollow point that was previously used.  I was offered a box of the ammo to test by fellow KTOG member Jason so I could run the new load through my testing protocol and see what we could learn about the new loading.

The photo above shows the new Corbon box and loaded rounds on the left.  The rounds in the center are the Speer Gold Dot loads.  The box and rounds on the right are the previous version of Corbon 60 grain JHP.  You can see that the bullets loaded in the new Corbon loads look very much like the Gold Dot bullets in the center.  The two close up photos below pretty much confirmed that the new Corbon is indeed loaded with the Speer Gold Dot bullet.


With this new insight on the latest Corbon 32 ammo, it was time to hit the range and see how the new load will perform.  For this test I used a KelTec P-32 pistol with a 2.5" barrel.

Testing Protocol:
My testing process is pretty simple.  I take one shot at alternate ends of a SIM-TEST block that is loosely draped with 2 layers of medium weight denim.  I take the shots from 8 feet away and impact velocity is measured 4 inches away from the SIM-TEST block.  My SIM-TEST blocks are now closely calibrated to ballistics gel density.  I shoot the blocks at the range and then bring them home and recover the bullets.  The video below documents the test from range to bullet recovery.


The recovered round was weighed and measured.  I've also included the stats from the test velocity string and calculated the ft/lbs. of energy of the test shot.  All the data is displayed in the sheet below.

One of the advantages of conducting tests like this over many months is that I've started to accumulate a deep archive of testing stats and recovered bullets.  The photo below compares three recovered rounds.  On the left is the round recovered from this test.  In the center is a previously tested Speer Gold Dot as loaded by Speer in their 32 Auto ammo.  When I tested Speer's load they were running a slow 818.5 fps average velocity that was too slow to cause the bullet to expand.  On the right is the old version of the Corbon 32 Auto that was recovered from a previous test documented HERE.  

Final Wrap-Up & My Thoughts
Corbon continues to push the speed envelop with their latest 32 Auto offering.  Every round tested from the sample box was moving 50 to 80 fps faster than the advertised 1050 fps velocity.  After looking back through my previous test data from the old Corbon 32 Auto loading, the new version exceeds the previous load by 30 fps for a 5 shot average (1113 vs 1083).  Unfortunately, the Gold Dot bullet can't handle that kind of speed and it exhibited significant fragmentation in the current test.  As the petals dropped, the core became lighter and lighter until it's mass was no longer heavy enough to drive it forward for deeper penetration and it came to rest just 6.25" into the SIM-TEST block.  Just an FYI, the old version that didn't fragment achieved 7.125" of penetration in my previous testing. 

I feel that Corbon is making a step in the right direction by switching from the old style bullet that expanded greatly, but suffered from core/jacket separation.  The bonded Gold Dot bullet solves the core/jacket separation problem, but introduces a new problem with fragmentation.  I think the Gold Dot hollow point bullet needs a velocity between the Speer loaded 818 fps and the Corbon loaded 1113 fps to consistently expand without over-expanding to the point of fragmentation.  My gut tells me that 950 to 1000 fps would be a great middle ground to experiment with.

Unfortunately, I don't think Corbon will ever see this test and the results.  If they do, I wonder if they will take the chance and down load the new 32 Auto to a more sedate velocity to enhance it's terminal performance.  If they do, I would try another test.  If they don't, then I'll pass on these in the future.


Disclaimer....This test should not be considered an endorsement or recommendation for the product(s) tested. It is up to each individual to make their own personal decision about 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 should not be used in any firearm unless the firearm manufacturer specifically states you are permitted to do so.  

3 comments:

  1. Hopefully Corbon will see this test and results. I just emailed them a link to the post.

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  2. One would expect the Corbon DPX round to solve the fragmentation/penetration problem. Do you plan to test this round?

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  3. It would be interesting to see the DPX results...

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