Hornseeker
Well I don't recall the actual measurements on sight movement but a good eye can discern a 1/4 moa click movement. IE click and your impact on the target will move. Thats with iron sights. You just have to learn to trust them.
As to how to do it. When I was really active I'd fire 8000 rounds a year. Thats not counting firing 12-44 rounds a nite prone with a 22 at 50 yards. Practice is what it boils down to.
floridahighpower.com is dedicated to competition shooting sports. When I was still shooting a lot I stayed there every nite instead of on hunting sights now that my goals have changed.
Also FWIW the national record with iron sights is 200-19x at 600 yards with a sling prone. X ring is 6 inches. So you can figure that group out. There are always lots of 200-16-18x groups shot each year. ( I say lots-- I suspect around 50 or more) I choose to use an AR which has more difficult sights and I've never shot over 17x But I was deteremined to fire a 200-20x and know I could have done it because I could tell each shot that was not an X as the gun went off. Then its a matter of not accepting those few breaks.(and being one with the wind calls.....)
I'm not sure what else to say. If your eye can see that movement in sights it can discern what you shoot at also. And you just have to sometimes aim at what you can see, and adjust sights to center hits. Which means sometimes folks aim center, sometimes at 6 oclock, sometimes at 12 oclock, sometimes at the frame,sometimes at the dirt where the frame meets teh ground etc... what ever you can see best. Heck in 1000 yard matches I've heard of folks aiming at another target because it was easier to see, and just adjusting sights.
Those that have not done a bunch of iron sight shooting will tend to never believe. Like I said, I was there myself. I just lucked into watching one of the nations top women shooters the first match I was sucked into and started doing everything she did. I had set high goals and met them. That was a combo of luck and determination.
Now I'm determined to win on the hunting scene somehow. Tell your buddies I've made some pretty long shots with both irons and scopes and every one had a disinterested witness. Not that I care any because I do it for me, not anyone else.
BTW how do you get better? Practice. If they would take a good iron sight gun and start shooting a bit here and there at highpower matches and determine to become good, then go back to a scope and see how easy a 300 or 600 yard prone scoped shot becomes. Practice the hard and the easier becomes simple. I used to think 300 yards was impossible. Then started shooting 1 to 1.5 inche groups at 300. I then looked to 600 and have shot a few test groups under 2 inches there. That makes 300 seem like a slam dunk.
Of course I'm human and still miss. Talk to last thursdays hog. Missed him at 125 yards with my AR. Had a horrible flinch right after my cousins 12 ga went off. The best even fail at times
If your friends still think its impossible, go snoop at FLHP site I mentioned and ask a few questions or get them too. You'll be dealing with the nations top shooters. Heck they might even admit to knowing someone like rost495. Might even tell you how my screen name came along...
Hope that helps, Jeff