The cans I regret buying:

YHM Mite - Was one of the first monolithic cans and I thought it was neat.  Turns out it was not the best 22 suppressor.  I still use it, but I wish I would have just bought an AAC Pilot or SWR Warlock back then

AAC Cyclone - Not necessarily a bad can, but I didn’t and still don’t have a great purpose for it.  It’s weight is the only real gripe I have about it.

AAC Cyclops - Suppressing a 50 is dumb.  Embrace the concussion and cleared out sinuses!  It was a big expense on an already expensive and impractical rifle.

I have a Specwar, but it goes with my 7.62 DMR.  I will definitely try it out on the 300BLK, but I am in a place now where every gun that gets a can, gets it’s own can.

Thank you to everyone for their response.

With quiet and lightweight being number 1 & 2 on the priority list, I have narrowed it down to the Q and Sig cans.

I run Sico's Specwar 762 exclusively on my 3 300 Blk AR's. 2 are 12" and one is 9"

For me it was a tossup between the Specwar's and the Sig 762Ti.

Short K or modular cans are no interest to me, as I'm after max Db reduction.

Plus all my AR's are set up for ASR mounts.

Latest and greatest 762 cans require the latest mounts, and unless I get them for free, I'll stay with my current setup.

Most of the latest and greatest cans are modular on the mount side(“Omega thread pattern” - 1.375”x24)... and ASR is definitely an option in that thread pattern.

ETA: Now you can go buy new cans!

Look at these guys. They sell the Omega and allow you to choose it without a mount or customize it to the mount you want: https://www.capitolarmory.com/silencerco-omega300-suppressor.html

I'm showing with no mount or accessories it brings the price down by $170 off retail.

It may not be the new hotness but it still is one that is hard to beat in size, weight and sound suppression. The Omega with a titanium direct thread and endcap. Next to it is a SDN-6 without its mount which would make it even longer and much heavier than the Omega:

I had Joe at Curtis Tactical make my dream SMG can that I use on full auto 9mm hosts but it is also OK for 300BLK.  With even supersonics....just not full auto with the supersonics.
I also have an Omega but the setup below is shorter than my Omega.  This can is only 5.75" long but due to the large diameter, has a lot of volume.
I'm using a 3 lugged barrel pictured below and the Bixler style 3 lug mount which doesn't use any springs and mounts rock solid.
http://www.c3junkie.com/?page_id=244

Not to derail this thread. But can you briefly explain how your 3lug works with no springs?

http://www.c3junkie.com/?page_id=553