The sight is held in by the dovetail, the distance between the sight and slide means you have a taller front sight probably to bring it on target,they sent me their shortest sight N/C but I put the taller one back on to put it back on target
My R1 was shooting low when I got it so Remington sent me a shorter front sight. I never measured the gap difference between the two sights but the shorter front sight seems to have less of a gap and that may be why the current gap doesn't bother me so much.
You are going to have minor variations in dovetail depth. A production front sight has to be able to go in. When you do a front sight on the Novak pattern that comes back to the rear you have to have some clearance or the sight will not fit. If you want a seamless installation on a dovetail front sight done to very exacting standards by hand, you will pay for that on the gun initially or in the aftermarket. No free lunch.