CELCIUS Training Weapon CTW M4A1 MX3 ris question

I am after a ris system for my new rifle.

I have read all the posts here but seem to get conflicting answers so asking same question again.
I am after a free floating ris system that would hopefully just bolt on, any help would be greatly appreciated.

I am looking at Madbull Daniel Defense M4/M16 12.5Inch RIS II, is that the correct size?

ehobby asia where i bought the rifle from told me it would not fit at all.

Hi, we have moved to http://tw-owners.co.uk

Thanks

I take it TW-owners.co.uk is no more, anyone point me in the right direction for the next best forum for all things CTW and DTW?

Cheers