Several people on different forums have reported getting denial letters from the ATF for their Form 1 application for making a silencer. The reason for the rejections is.
Attachment 85311
It doesn’t seem to have anything to do with solvent traps because the people submitting the applications are not tell the ATF that they are making them out of solvent traps.
I submitted my latest form 1 on the 11th of Feb and have not heard anything on it yet.