I got a good deal on a TA31RCO for the M4. However, I plan on using it on my M16A4 clone. Now I understand the BDC for this model is supposed to be matched with the M4 shooting M855. Can it still be made to work on the M16? 
The BDC on the M4 variant is taller than that of the A4 variant, because of the difference in barrel length, so your BDC will not match up.
That’s not to say that it “won’t work.” Zero it per the TM @ 100m using the tip of the chevron. What you’ll likely notice is that your 300m and beyond shots will have a POI higher than the POA at a given distance. EXAMPLE: you take a 500m shot using the 500m POA, the round will print high, but it will do it consistently, which is something you can track.
All you need to do is shoot the thing, note your holds, remember what they are and use them. It can work. Hell, you may even be able to find an ammo that will get it to match up pretty close, with experimentation. Not greatly likely, but possible.
+1
btw, keep in mind that even the right bdc/barrel combo isn’t 100% accurate