Now that I've got my NFA trust set up and my SiCo Omega on the way, I have decided to SBR one of my lowers and try a 10.5" 5.56 upper.  I would like to run the can under the float tube, and I would like to know what model(s) you have tried in this application.  It needs to fit the can, but I don't really like the quad rails that are super fat.  I like the modular rails that I currently own, but they are all under 1.5" ID.

What do you have?

Assuming you're referencing 5.56, there will be a lot of heat transferred to the rail by running the can under it. That being said, I'm using a 12" Seekins MCSR on my 8" 300blk build...

Ive read about this as well

Seekins BAR / MCSRV2, Samson rails should all fit - BUT I wouldn't put a suppressor under the handguard on a 5.56.

Put a mag through your rifle with the can on it and see if you really want to touch it. That heat is pretty much going to transfer to the rail.

The new primary arms hand guards made by seekin would work also.  I plan to use one for a 9mm build.   I wouldn't do it for 5.56 though because the can gets really hot.

Suppressors under the rail look cool but you run into two issues...

1) The excessive heat generated from firing 5.56 or any centerfire cartridge makes shooting the rifle uncomfortable or painful after about 1 magazine, i believe its 8 degrees temp increase in the suppressor per shot fired, so 240 + 72 = 312 F after a single mag. Do-able with rail covered and gloves but after the second you will have to stop shooting.

2) Because of the excessive heat most people dont hold or mount anything near the suppressor so you have probably 6" of unused rail, which is now just extra weight (and cost)

Im not saying it cant be done, especially if you're the person who goes to the range and shoots 100 rounds or less, but if you bring a ammo can with you every time and like to push your rifle hard then i would recommend running the suppressor in front of the rail.

unless you are going DT you cannot put an omega under the handrail unless your cuts on your rail are so big you can actually engage the locking ring using the ASR mounting system.

Past that you dont wanna put 556 under the handrail.

Thanks for the feedback, all. You've changed my mind on the rail covered can idea.  I like the clean look but I hadn't thought about the heat of the can nor engaging the ASR.