H2 usually works fine. I have a H3 in mine with a red springco spring, but I also use a FRT trigger with a suppressor as well with an adjustable gas block. Needed for the suppressor and frt trigger. But if you’re running a normal 10.5” a h2 should be fine. If you want to slow it down a little more or maybe ease up recoil you could easily use a H3 buffer with a 10.5 I can shoot semi and remove the suppressor on my 10.5 without any trouble even with the h3 buffer and red springco spring. Still runs just fine.