I went to the Winchester Gallery in Fort Worth, or at least close to Fort Worth, today. I'd never been there before and they have one of the largest collections of handguns I've ever seen.
Had a little discussion with the man behind the counter about short barrel weapons. I've always like long barrels. I seem to be much more accurate with the long barrel. I've heard some people say that it is because of the sight radius. I assumed they meant the front sight was out there further and therefore easier for me to focus on.
I've always been amazed at how accurate my 3.5" Kimber is, and I mentioned it to him. He stated that short barrels get a bad rap, and they are accurate, the problem is with the shooter. That with the shorter barrels the sight radius is decreased, meaning the sights are closer together, which makes it harder to get them aligned properly.
I can't picture this in my head why having a greater distance between the two sights would make it more accurate. I've noticed some rifles where the rear sight was quite a distance forward from the rear of the gun. So if a greater sight radius gave more accuracy it seems like the rear sight would be back as far as possible.
The sight radius is based on the assumption that you can ony put the blade between the back sights to some accuracy.
Lets say for arguement's sake that I shoot very poorly and can be an eighth of an inch off from front to back. Over 3in, that puts me about 2.4 degrees off target. If I have a rifle with 18" between the front and rear sights and I'm an eigth of an inch off, now I'm only 0.4 degrees off target. Much more accurate. I've attached a rather poor (not to scale) illustration of what I'm trying to explain below. The two lines show the same distance off the front sight at differing radii.
Know more than you say, Have more than you show. - paraphrased from Shakespeare
Well, a "picture is worth a thousand words" is true in this case. From your drawing it is quite clear. The guy at the gun store was right. All my life I've had this fear that eventually I would be wrong about something. It has finally happened. Glad that is now behind me. ;D