Saturday, February 2, 2013

Terminal Ballistics Testing Update - Stress Test v2.0

Range Update:  I've been incredibly fortunate to have nearly exclusive use of local range space whenever I want to do a some terminal testing or make gun review videos.  During some marathon range days, I've tied up the bay for 6 hours or more and have never been rushed to complete my work because someone else wanted to use the space.  The bay was very large and lighting for video work is always good because the business end of the berm faces south. 

Over the last few weeks the bay has been undergoing a major reconstruction and I had the chance to walk the bay last weekend.  I'm not really sure what they think I might want to test in the future, but I'm pretty sure I'll be set up to test just about anything civilian legal in this monster space.  The berm walls are being raised and the bay floor dropped so when it's all done I should have 18 to 20 foot tall walls on 3 sides.  I'm pretty excited about the upgrade.  It will be nice to be able to position 6 ft tall targets in the middle of the bay and not worry about the possibility of shooting over the berm.  The video below will give you some idea of the size of the bay and status of the project.  They still have quite a bit of dirt to move, but it's coming along very quickly.


Test Protocol Update:  Many of you have asked why I stopped using two layers of denim in front of my test media block when I switched from SIM-TEST media to the new Clear Ballistics Gel test media.  The primary reason for that was to keep the gel as pure as possible for as long as possible.  I don't talk about prices very often, but a 16 x 6 x 6 Clear Ballistics gel block runs $130.  My fear was if I continued using denim in front of the block it might get so full of threads after 2 or 3 uses that we lose the primary benefit of the gel, which is its clarity.  That didn't seem like a good return on my investment in the gel.

As I continued to work with the gel I've now got a better understanding of how to properly clean it up and prep it for reprocessing.  I can't get every last piece of gunk out of it, but I can clean it well enough to get at least 5 or 6 recycles from the block.  It's still much more expensive than the SIM-TEST media, but the added visibility of what happens inside the block is well worth the additional cost.  Then there is the additional benefit of the consistent density from block to block that removes that variable from the test results.

I always planned to get back to testing with a "clothing barrier" in front of the block, but I didn't want to stick with the 2 layers of medium weight denim I had used in the past.  I wanted a more realistic clothing  barrier.  Something that you might reasonably expect to encounter in the real world that could put some real stress on a bullet. Back in early December I published my first stress tests that used 3 layers of tanned 2 ounce pig skin that was backed up by two layers of medium weight denim.  I published those test results HERE.  During that testing, we discovered that the leather would actually cause a small explosion inside the gel block as is was dragged down the wound channel by the bullet.  This made a heck of a mess inside the block.  I had to clean up the denim dragged into the block and cut out and discard all the burned/scorched gel.  I couldn't quite figure out why we were seeing those flash explosions, but I had a theory.

After studying the two different animal hide tanning processes most widely used today, I determined that pig skin had been processed using the mineral/chrome tanning process (chemical processing) so I needed to try some vegetable tanned leather (more natural and less chemicals) and see if that made the explosions go away.  The Hermann Oak Leather Company in St. Louis, MO still uses the vegetable tanning process.  Their grading and quality assurance are also top notch.  Many high quality leather holster makers will only use Hermann Oak Leather for the construction of their holsters.  It didn't take me long to locate Springfield Leather in MO and get my 2 square feet of genuine vegetable tanned Hermann Oak leather.  That should be enough leather to run many tests.

I measured the thickness of  the three layers of the 2 ounce pig skin I used in the first test and matched that to a single thickness of 5/6 weight Hermann Oak Tooling Leather.  The new stress test barrier has a 3/32 inch thick leather piece backed by the usual 2 layers of medium weight denim.  I've got a picture of it below.    


I tried the new barrier material for the first time last weekend.  As you can see in the two pictures below, I'm still getting explosions inside the block.  The good news is that with just one thicker piece of leather, I only have one leather disk being dragged down the wound channel instead of the three disks of leather with the triple ply pig skin.  Less total leather surface area kept the flash explosions smaller this time around.  I'm still going to lose some gel every time I run one of these tests, but hopefully I can control my losses.  I think I've isolated the root cause of the explosions and it's the fat liquor treatment that all leather gets during tanning.  Without the addition of fat liquor, leather would lose all flexibility.  Have you ever visited the American Leather Chemists Association website?  I have.  I didn't even know they existed before researching the fatliquoring process.  Internet = Best Invention Ever! 



I will tell you now that the stress test lives up to the name.  I did my homework when I picked the barrier materials.  I don't think anyone will dispute the barrier materials are "real world", but I'm anticipating all the hate that will be heaped on me when people see how their pet loads perform, or don't perform, after running through the barrier.  That's ok, I don't mind the hate.  I think my "Why I'm Not Excited About the Smith and Wesson Shield" video may be the most disliked gun related video on YouTube so I'm developing a thick skin.

If you like the stress test protocol, I'd like you to please do me a favor.  Please go visit the Facebook Page of the Clear Ballistics Company and let them know you read the PGAG blog and support stress testing.  You can link directly to their Facebook page by following this link.  Clear Ballistics on Facebook  I've been working on the two owners of the company to cut me a hot price for some of their less than perfect gel.  This is gel that may be slightly off color or have some "floaters" in it.  It's good gel, but just not up to their quality specification.  The more of this "less than $130 a block gel" I can get, the more likely I am to do more frequent stress tests.  Just post this on their Facebook Wall "PGAG Blog sent me and I support stress testing."  I'm sure if they see enough messages like that they will see the light and cut me some slack.  I currently have one block set aside for stress testing.  It would be great to have 3 so I could do both bare gel and stress testing  on each load.
 
Testing Schedule and Ammunition Supply:
I did my best to secure the future of the blog over the last year.  Having experienced the previous ammunition drought, I thought we might see another one in 2012 after the election.  I bought as much as I could afford to buy in the 6 months leading up to the election so I still have stuff to test.  At my peak last year I would sometimes publish 3 tests a week.  For the duration of the drought, I'm going to limit my tests to one per week.  It will always be published on Thursday.  So you have 48 more Terminal Test Thursdays to look forward to in 2013.  I do reserve the right to publish more than one test per week if a special situation comes up, but you can bank on a minimum of 52 tests this year.

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