No, you do not have to reset zero, at least with iron sights, because the sighting system is part of the upper......or it should be. If you want to use one optic for both uppers, then yes, you would have to rezero each time you swapped the optic from upper to upper. But the 9mm upper I linked to already has an A2 front sight on the gas block, so you could buy an inexpensive Magpul rear sight — approximately $50 — and leave it on the 9mm upper. Unless you have bad eyesight like I do, iron sights for 9mm would be fine for any distance you're likely to shoot a pistol caliber weapon.Abraham wrote:TAM,
That's an intriguing idea.
Thanks.
So, what are the further considerations to doing that?
Gotta buy magazines (not a problem) and reset zero (again, not a problem) every time I oscillate back to 5.56 upper?
What else, if anything, do I need to consider if I go this route?
And, thanks again.
I really appreciate it!
Personally, I'd probably buy a dedicated micro red dot like the one in the picture. Again, you don't have to pay Aimpoint Micro prices ($500-$600) for one. Primary Arms, Vortex, and Bushnell, among others, all offer micro red-dots at cheaper prices.
Here's a link: http://www.9mmar.com/