As has been mentioned the accuracy of the pistols depends upon the ability and time spent practicing by the shooter. Years ago I carried a Model 66 4" S&W on duty and a Model 66 2 1/2" Off duty and back up. Obviously we had to qualify with both. Both were agency weapons. When in CID I carried the 2 1/2" I found that the Model 66 21/2 was as accurate as the Model 66 4" at anything up to 25-50 yards. As the guys have mentioned, obviously the 4"or 6" Revolver has a longer sight radius which is easier to align at longer distance but the bottom line, if the rear and front sight are properly aligned the only effect would be muzzle velocity and energy at various ranges. But also as mentioned the 2 1/2 is easier to conceal and carry than the 4 or 6" revolvers. I also carried my 2 1/2" in an a GALCO ankle holster which I got accustom to the weight of the Model 66 2 1/2" and hardly noticed it. So the real point is the purpose you want the weapon for is a big factor. If for target or plinking only or protection at home stored in a drawer or security box The 4" or 6" would be a better choice for the average person. But if it's intended purpose is for personal protection and concealment the 2 1/2 would be my choice. Either I am sure you will enjoy the weapon you choose. But I also like S&W over others for a Revolver choice. Just feels better to me but nothing wrong with the Rugers if you like those. Best to go check them out for feel balance and other issues before you buy! If you have a range around that rents them that would be a good thing to check out!
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Today, we need a nation of Minutemen, citizens who are not only prepared to take arms, but citizens who regard the preservation of freedom as the basic purpose of their daily life and who are willing to consciously work and sacrifice for that freedom."
-- John F. Kennedy