Making a DD rail fit on an ICS m4- will drastic measures need to be taken?

[crunkathon2k]

my DD rail replica won't fit on my ICS m4. The threading seems to be different- I knew that would happen, and I expected filing to do the trick, but it didn't. Also, the two notches on an ICS m4 barrel prevent the locking collar from sliding through.

 

I am thinking of supergluing the barrel into the upper, and supergluing the locking mechanism that the locking collar bolts on to the upper as well. That is a permanent solution, and sounds really stupid, so I was wondering if ther was something else I can do.

 

For other ICS owners, take this as a warning that DD rails may be incompatible.