The test was as follows:
Take an HK-416 and fire eight magazines. First mag semi auto, second mag full auto, third mag semi auto, etc -- for 8 mags. Then let it cool. In the real military test, they did not let the can completely cool. In this test, we did.
Repeat this three more times, for a total of 960 rounds. The idea is that eight magazines is a battle load, so this would simulate four firefights. It is a tough but reasonable test for a serious user. All six of our silencers survived this test.
First problem -- the G5 flash suppressor is not HK-416 compatible. We were able to get it to work with spacers (not recommended, but we checked it after a few shots and there was no bullet contact).
I videoed the entire test. I am away from home, and may not be able to post the video until next week, so I will give a report for now:
During the first eight mags, it was clear the can was not going to survive. It seemed to be puking it guts after five mags and big fireballs were coming out of it. Around this time, the mount came unscrewed on its own (not the flash suppressor, but rather the part in the middle of the can). I could call this a failure, but since we could tighten it, we decided to proceed.
We let the can air cool for about 10 minutes and then helped the can to cool completely with some water. Then started with the second 240 rounds. Then we let it cool completely again, and proceeded with the third batch of magazines. Then we let it cool completely once more, and started the final batch of mags.
Two magazines into this, I noticed the can seemed to be bulging in the middle. I shook the rifle and could see the can flopping around limp. I halted the test and noticed that the roll pin which holds the mount to the silencer main body failed, and the can unscrewed. I stopped the test six magazines early as this was a catastrophic failure and not field-repairable. This is an area that I would recommend be welded.
We let the can cool, and could hear parts shaking inside. I was surprised because Gemtech has told me that for the last few years, their silencers were welded inside. The mount halfway unscrewed on its own, and had I not noticed it, I am sure it would have blown down range.
I looked into the back cavity and I could see the baffles were not secured. We tapped the can and the baffles all fell out. As you can see from the photos, there is no evidence of any welding at all. Also the roll pin which holds the Inconel insert into the stainless blast baffle (apparently a cost-saving measure from using a real Inconel blast baffle) cracked through the side of the baffle. I also noticed that the Titanium around the flash suppressor area had fractured in several places. Again, no surprise as Ti is not a high-temp metal. See this: viewtopic.php?t=4780
The spring in the BiLock mount, by the way, has lost its strength from the heat. That makes sense, as springs are generally only good to 600 degrees, so one would expect them to fail if you put one inside the blast chamber of a silencer.
The claims of one vocal critic who has not looked closely at the G5 mount notwithstanding, the spring is not subject to the heat and flame of the entrance chamber. It is not only isolated from the entrance chamber, but our thermal measurements ahow that it remains minimally cooler than did the spring in the older M4-96D (where we had no spring failures either).
Philip H. Dater
The G5 mount never got stuck for me during this test, as has happened with the M4-96D mount.
Click for larger images.
Not welded. PhD of Gemtech told me they have been welding cores for a few years but that does not appear to be accurate.
Stainless blast baffle with Inconel insert in center. Pinned in place.
Cracks, chips, and fractures in Titanium.
Cracks on back of blast baffle.
Hole around roll pin has failed.