Hi.  I bought two Aero Precision M4E1 upper receivers ( http://tinyurl.com/q9j8x8r ) which I intend to build them up.

I would like to consider options besides the ones offered by Aero Precision ( http://tinyurl.com/ns3ph5s )

Someone told me that the Aero Precision BAR barrel nut  ( http://tinyurl.com/p2agc5r ) used to mount their rails is also fully compatible with the
Seekins BAR Handguards ( http://tinyurl.com/pthn2yx ) and also Spike's BAR2 Handguards ( http://tinyurl.com/q2kvoh9 ).

Can someone confirm it is true?  

Is the Aero Precision rail mounting system maybe compatible with the rails of other manufacturers?

Any information will be most appreciated.

Thanks!

Calacaroja

Correct. Seekins BAR quad rail and MCSR handguard are compatible as well as the radical firearms and primary arms handguard.

Perfect. You gave me more information than expected, Was not aware of radical firearms and primary arms hand-guards being compatible. Thanks a lot!!!!!!!!
Best, Calaca.