I have an Obsidian .45. You're right about the Rugged three lug adapter. The problem that I had with it was that when installing the can on a firearm with a three lug barrel, you have to be extremely careful to make sure it seats properly. First time out, I managed to rotate the can/adapter too far, didn't realize it wasn't seated, fired the first round and blew the can downrange.
It was at an indoor range and of course it landed on the concrete floor at just the perfect angle to damage/bend/swage the front edge of the tube inward, making it impossible to get the end cap off, ever again.
I called Rugged about it. They can't legally send out the front tube as a replacement, so I had to send the whole can back to them. They were very good about replacing the tube and end cap under warranty and turning it around quickly.
I talked to one (the only one ?) of their CSR's and suggested that they needed to improve their three lug adapter so that it can't be "over-rotated" and more so, build their end caps with a crown on them to protect the front of the tube. The guy could have cared less. Didn't give a shit. That came across very clearly.
Oh, and re-design the end cap and back cap so that standard tools (Box, Open end or Crescent wrench) can be used, instead of those proprietary adapters (that appear to be made out of Nylon/Delrin/UHMW). They charge for the adapters, BTW.
Am I happy with the Obsidion ? Yes, with conditions. It is well built, but........man, they need to fix the design flaws.
Would I buy another Obsidian ? Uhhhh, probably not. At least not until they've shown that they have started listening to their customers input and improve their products accordingly.