SD Tactical is not shut down. They still sell anything that can't be used to build a silencer straight up on their site.
http://sdtacticalarms.com/ I get emails once a week or so with new products from them.
You can still buy "solvent trap" parts from him as well, once you have your form 1 in hand. SDTA is not quite as polished and it is "off the shelf" so options are slightly limited but adequate. He sells muzzle brakes, adapters and boosters now too.
DM stuff seems to be higher quality and he will make your stuff to order, DM's backlogs have been running very long from what I understand.
FWIW, I built 2 form 1 cans with SDTA titanium tubes and end caps and titanium VSRs off ebay. couldn't be happier for the cost.
I waited until I had the tax stamps in hand before I ordered anyway, because their availability is usually very good.
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