Recently, we had a batch of 1/2″ AR500 targets cut which we ended up questioning the actual material hardness. Every batch of material we cut into targets includes what we call a QA/QC Blank. Two overlapping 6″ circles, with two bolt holes. Simple, but not something people ask for as a target so it’s easy to pull from each sheet, label for the batch, and have available for testing.
We’ve done this before and written it up, when it was a question about 5.45x39mm, but that’s been almost seven years ago. https://moatargets.com/blog/qaqc-testing-moa-steel-with-5-45x39mm/
This test was prompted by a hand written note on one of the piece of material, which seemed to indicate it was AR400.
We could do the research, find out about the heat number, back track all that, and still not know if they grabbed the wrong material, or the wrong paperwork. So we tested the actual material.
Testing method is pretty simple. Taking a known standard of AR500 material, in this case, a blank from 2017 from a known batch, the material to be tested, and some additional material for comparison, head out to the range.
We chose to use our standard A-Frame Brackets to mount the testing materials. https://www.moatargets.com/in-stock-targets/2×4-bracket,%20target-stand
Testing materials were hung from the 2×4 crossbeam with our 12″ firehose kits, which include the hardware shown. https://www.moatargets.com/in-stock-targets/firehost-steel-target-mounting-kit
Testing targets as set up on MOA Targets A-Frame Brackets and Firehose Kits. Similar to the MOA Starter Kit which would include the brackets, firehose and hardware, and one 8″ gong of 3/8″ AR500.
At the range, we set up at 100 yards. Using factory (GECO) 5.56x45mm ammo with an estimated muzzle velocity of 3000 ft/s from our 16″ test bed rifle (previously chronographed), we should have an impact velocity of approximately 2800 ft/s at 100 yards. 2800 ft/s is the typical damage threshold for hardness 500 steel (AR500). Four QA/QC plates were tested. The known standard 3/8″ AR500, a known 3/8″ AR400, a known 1/4″ AR400, and the questionable 1/2″ piece that is the true subject of the test. Testing results below:
The last photo, with the targets painted white, was after moving out to 150 yards. At 150, AR500 should no longer take even the light surface pitting you will typically see at 100 with a 16″ barrel and standard velocity 5.56x45mm. In this case, our 100 yard results were inconclusive enough to move out to 150. At 150, both the known standard 3/8″ AR500 and the test subject 1/2″ material ceased to show damage, while the 3/8″ AR400 continued to show damage.
As velocity based damage is a result of exceeding hardness, not thickness, our conclusion was that the subject 1/2″ material was indeed cut out of AR500 and we could go about our day. Scroll back up and note the dent in the 1/4″ AR400 material, not only did 5.56x45mm pit the target, it bent is as well. That’s not observed on the 3/8″ or 1/2″ material, and is the subject of another blog post. https://moatargets.com/blog/14-ar400-as-a-long-range-rifle-target/
We hope this has been a useful writeup for you guys. We had fun shooting stuff, got to confirm that our QA/QC methods work, and enjoyed some nice desert air.