Trying to find a post.

I’m trying to find a post about a members run in with the ATF and his supressor project. I feels like I just read it but I can’t seem to find it. Basically, I remeber in the post he stated that the ATF agents took his supressor and were going to run some tests on it. Do any of you remeber what kind of tests they were? In the end they told him it was a firearm silencer. Any help would be appreciated. Thanks!