[ryandarr1979]

Here is my 416 11” compared to a Caracal 816A2. The height over bore as I can tell are identical. You’ll notice the Caracal’s MLOK rail isn’t as thick as the quad rail as the quad rail bottom rail sits below the pivot pin. The rail clamp bolt is absent as well given the MLOK rail secures in the top rail of the Caracal’s barrel nut with two hex bolts.

 

[ryandarr1979]

experiment time! can you put the HK rail on the Caracal to see it its the same? for science!

I’ll check but pretty sure the barrel nut is significantly different. I don’t think you can use a 416 barrel nut on the Caracal barrel either because of the piston system. Extensive gunsmithing is likely. Why would you want to anyway, given the Caracal rail is superior unless you just prefer 1913 quad rails (which I can appreciate).

 

[ryandarr1979]

I removed the rail from the Caracal upper and tried to install the HK416 rail. It won’t clear the 816’s gas block.

 

[ryandarr1979]

The 816 rail doesn’t actually attach to the barrel nut. The two tension screws press against a removable steel insert that sits in a pocket on top of the barrel nut above the piston rod. The two hex screws simply anchor with tension, but its a rock solid system. It of course also has an anti rotation feature so loss of zero is a non factor. My only complaints are the proprietary nature and lack of rail upgrades and 2. The requirement of a hex wrench to remove the tension screws, instead of a tool less system like HK or Geissele (or the Haenels) use.