they can do it like vegas 2 where you only see iron sights when you aim
Well, when your view switches to only see the iron sights when you aim, you aren't technically in 3rd person any more, are you?
Because in games, it is easier for some people to sight in with them. I also preferred using scopes on my handguns in Borderlands, but mostly because their gun sights were nonexistant or svcked. The funny thing is, in life, sighting with scopes is usually harder, unless you're sighting in on an unmoving target. Not the get the crosshairs on the target part, but the hold the gun right, align you eye to the scope and aquire the target part. It is unnatural for the human eye to fucus down a tube. All depth perception is lost with the reduced field of view. Alternately, shooting over open sights should be harder, as you have to not only aquire the target, but also align the front and rear sight, something not modeled in computer games. You will always get perfect sight alignment in FO:NV. But for some reason the game machanic doesn't allow for the hand-eye coordination that simply take over when shooting a weapon irl. Without much thought, you bring the weapon to bear, align the sights, aquire the target and fire lin a blended motion mostly controlled by your relexes. It doesn't work that way in games. Because you're looking at a 2d screen, the depth perception that rules your reflexes is removed.
This. So much this. Most people have very little understanding of how sights work in real life, or how to focus your eyes to use them. In video games all the work is done for you. I would find it hilarious if you had to BZO each weapon after using a scope mod, or else all your shots wouldn't hit where you aim, but most movies and games ignore this.
I can pretty much guarantee they aren't in the game, but some company (don't remember who) makes a rail attachment that's actually just more rail, but offset at a 45 degree angle, but still in line with the barrel, you can mount anything you want on there. Jerry Miculek uses that with a red dot sight in conjunction with the scope on his rifle in competitions so he can aim at near and far targets without wasting precious time switching weapons. Not exactly scope and "iron sights" but i guess you could mount the scope at the 45 and leave the top bare.
I hate rails on weapons. I don't want to have to mess with adding a crap-ton of modifications for a weapon, or worse, having to remove them before using the weapon. Before I left the Marines, we switched to the M16A4, which I didn't like at all. Except for the unnecessary rail system, it offered no improvements over the M16A2 I had been using for years. The A4 wasn't accurate as far out as the A2, wasn't as lethal as far out as the A2, required you to redo your BZO any time you messed with the top slide rail, and had a stupid front handle that no self-respecting Marine appreciated - everyone unscrewed it and tossed it in a seabag as soon as was humanly possible. It screwed up the execution of every firing position you'd ever been taught, and made the weapon awkward to use with a sling. I guess I just like things plain-Jane vanilla. (Or, alternative theory, the A4 just svcks.)
That said, I plan on using weapons mods in New Vegas, because I can enjoy all the benefits with none of the drawbacks. I will continue to always hate slide rails. (In MY day we got by just fine without those things ya young whippersnappers! Rabble, rabble, rabble . . .

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