Don't over think it bud. I have a QDC suppressor because I shoot only Knight's AR's. So yes I did get a can to match them. They are not the quietest, nor the lightest, but they are built like tanks. Hence the reason I considered it a life time purchase.
I do feel the 338 can is a waste, but its your money. I have a 338 LM also and rarely shoot it. 50 rounds at the range will beat you to death. A 6 or 6.5 is where the money is at. Shoot all day with no fatigue.
First can purchase should be a 30 cal and a 22LR. 22's are just too much fun while waiting for your barrel to cool off and plinking around. I would go TB or DA. I shoot the DA Ti on my bolts now with no shift from off/on. Also, I have 2 TB 6.5 ultra 9's in jail for the last year that are the CB mount. Since I shoot mostly 6/6.5 I wanted the most suppression possible.
Dead Air makes very nice cans, don't be afraid of them. I know everyone here says just buy TB, but what you will find is the "tone" makes more difference than ~1.1 DB less over another can.
There is a guy that comes to the local matches that has a can with ports on the front edge of it ??...and somehow I usually get put next to him.... HE BLOWS MY FUCKING EARS OUT...so much that I have to put my ears on with all of us shooting suppressed. It's very sharp and high pitched. Don't be one of those guys. Also, while the harvestor is a good can, the tone is not that low with it. Both TB and DA cans are all low tone's and meter well.
Since this is going to be your first can purchase, I would do this:
If it will spend most of its time on an AR platform, get the Knights QD or Sandman L QD.
If your going to toggle it between a bolt and semi, get the Sandman L QD
If you want to future proof yourself...well get the Sandman L as total cost of ownership will be less. Mams get pricey after you have to buy one for every new gun you add to your stable.
If you want a Knight's can, go buy a SR15 and throw the 556 QDC on it to satisfy yourself.
For the 22lr, either buy the TB or DA, they are almost the exact same design and sound the same.
After you get your first can, you will wonder why you did not do it sooner...which leads to you buying more cans. Hardly anyone has just 1 can.
Personal notes.....
I now do not like shooting with guys who are not suppressed.
wtf !!! Why did I not do this sooner, I have bad hearing anyway.
I have 7 now, and will continue to add more.
The wait sucks donkey doo. I"m glad I did not buy just one when I started this journey. You will feel like crying after you shoot one for a day. More is better.
As a KAC fanboy, I 'm glad I have one for my AR's, but I do not think I would like using it for all long guns.
22LR suppressed shooting rocks !!!
Let me know what ya think bud. Everyone's journey is different.