For a .223, I would suggest the 1-4 MTAC over the 1.5-6. I own every single offering in the MTAC line and I honestly think they are the absolute best line of scopes for the money, bar none.
The 1-4 MTAC on a .223 is good out to 600 yards. It is what I use on my match 3G rifle and I have placements in the top 10 on long range stages at majors, even though I am not a top shooter. The reason I say go with the 1-4 over the 1.5-6 is because of the true 1x. Inside 50 yards, the 1x is faster on target and transitions and is SO much better for shooting both eyes open.
My 1.5-6 sits on a .450BM I use for hunting and so close in speed on multiple targets is not needed (I hope).