Originally Posted by
AndyLate
OP, your original post isn't terribly clear.
I thought you wanted to:
1. Keep your complete A2 upper as-is
2. Purchase an A4 rifle
3. Swap your A2 upper onto the lower of your A4 rifle
4. Retain the A4 upper for when you want to use optics
If that us not your plan, please be clearer.
If that is your plan, then confirm it.
My answers are correct in a general sense but Iraqgunz has a great amount of expirience and encyclopedic knowledge of the AR and can provide more specific answers and help you avoid unexpected pitfalls.
Andy