Good evening.

I previously posted couple weeks back about 300 BO barrels.
I ended up purchasing a ballistic advantage 9.5" pistol length barrel.

My question now is...
I'm leaning towards getting the Hybrid from silencerco.
Ideally, I'd like the can to fit inside the rail.  (Not the whole can)
I've also read I need a blast cap so when I don't run the can, I don't damage the rail.
So.. Do I need a bigger rail in diameter? If so what measurement? And how much of the can can I fit inside the rail? I was looking around 2-3" being the hybrid measures 7.8"

If I were you, I would re-think trying to fit the can under the rail.

I just built an 8.5" 300BLK with a 7" rail and I don't find it too short, heck the compact package is half the reason to own an SBR.