Good call on the Thompson Machine Op series. The 10/22 with an integrally suppressed barrel is AWESOME. Even with normal ammo it shoots subsonic. Another big plus is Brooks. That dude rocks and his service is awesome.
I own over a dozen suppressors, including popular brands like Surefire. My favorites are my Thompson Machine cans, hands down. They are so easy to disassemble and the mono-baffle stack makes it a 1 minute job to service them. They happen to be cheap, but that's not why I like them.
Also look at the Thompson Machine Op-B CZ bolt action integrally suppressed ported barrel .22LR. That gun is crazy quiet and accurate. I can shoot with folks having no idea that I fired. One guy even asked me what kind of airsoft gun I was shooting! The 10/22 is more fun for lots of fast shooting and you can get much larger mags and accessories, but the OP-B is great for kids and precision shooting.
In response to your question, I've bought both the barrel and the complete Op-C. The barrels appear identical and they sound equally quiet to me. My guess is that they are the same, so if you want a special stock, get just the barrel.
BTW, I also love the TacSol SBX, which marries well with the 1" TM suppressors. That said, the SBX stays in the safe and I regularly use the Op-C. Between the two, it's more fun, a better shooter, and it's better disguised than the SBX.
Have fun! Hope that helps.