Re: what power scope?
Folks buy scopes because they perceive with a scope they'll hit what they're aiming at. They know they can't hit with irons, at any distance beyond the distance a target could be hit intuitively; and, therefore, they think the scope is the answer to hits at distance. After all, they can see the distant target better with the scope; plus, with the scope, they can recognize an exact target/reticle relationship. What they don't know is the target/reticle relationship may not describe where the rifle is pointed, or that after getting a relationship there's anything else which needs to be summoned for a good hit.
Leaving the range without a good hit at distance, these folks are heard to say, "that gun don't shoot"," my scopes' broke", or, "that gun shoots better than I do". They don't seem to ever think their problem has anything to do with not knowing anything about good shooting, or that the scope is not a substitute for not knowing anything about good shooting. Fact is, these folks can leave the range and still hold on to the notion that they're big time marksmen. The tiny groups they shot with their scope earlier in the day at 100 yards convinced them of that.
These folks have been deceived by the scope, and it has distracted them from what's really important-knowing where the barrel is pointed. Instead these folks think, perhaps, with just a little more magnification their groups could be even smaller.
With iron sights, a shooter has no delusions that he's a marksman. He will miss at any distance. But, it's this recognition of not being able to do it that, when the scope is not tempting such a shooter, will force the shooter to learn how to get the job done with irons. And, when the shooter finally realizes he can get good hits with irons to as distant a target as can be seen, the scope looses much of its appeal.
Sure, magnification can be an aid, but at some point, setting the power ring all the way up does not assure a better result. For example, with a 16 power scope you could locate a golf ball at 600 meters, and, if the reticle did not cover the ball, a shooter could certainly aim at it with confidence he indeed was aiming exactly. However, that golf ball is less than a 1/4 MOA at such a distance, so, unless the shooter has an amazingly accurate rifle, the only value in magnification is in revealing to the shooter that he did not hit the target.