My draco was purchased 2 years ago.Instead of going thru the sbr paperwork,I installed a flash supresser that brought the bbl length legal to install the ace folding stock.I am retired law enforcement and its all legal. My original question was to ask if the opap I just purchased had a slant or straight rear trunion .You just picked it up and you don't know? And then there is the form 1 issue, that should take months to get back.
The Manticore Triangle Stock and Stormwerkz hinge are actually aluminum and not steel, but yeah, they are all metal!Website says for use with all Ace Receiver Blocks.
I would take a look at this thread:
MA-5100 Triangle Stock
The Manticore triangle stock will bolt right on to your receiver block too and it's all steel not part plastic..
Although I elected to mount mine fixed and not fold I've been pleased with it.