Cornerpocket Posted October 21, 2012 Share Posted October 21, 2012 I pondered this about two in the morning when I couldn't sleep the other night. It is widely accepted that, all things being equal, a longer sight radius on a pistol enhances accuracy. While this may not be a function of the mechanics of the gun, it seems to be generally accepted that most folks will be more accurate with a longer barrel. On a Smith and Wesson 686, for example, you will probably have greater accuracy with a six-inch barrel than with a three inch barrel. I accept this and do not argue the point. My question is, why? A couple of factors would seem to make greater accuracy with a longer sight radius counter-intuitive. First, the rear sight is at a constant distance from the shooter's eye. In my 686 example, the only difference is that the front sight is 3 inches further away from the shooter's eye on the six-inch model vs. the three-inch model. The shooter should perceive the front sight as narrower given its further distance from his eye. With the rear sight still perceived as the same relative size, it seems that, from the shooter's perspective, he should have the perception of more daylight on either side of the sight which is six inches away and have greater difficulty getting the "smaller" front sight centered in what he perceives as a now relatively "wider" rear notch. Second, recoil starts as soon as the powder in the cartridge ignites. The gun is recoiling while the round is still in the barrel. A round fired from a six-inch barrel will be contained in the rising barrel longer than its counterpart in a three-inch barrel. If recoil is pushing the barrel up and that effect is occurring the whole time the round is in the barrel, it seems to me that the round fired from a six-inch barrel should be expected to land higher than one from the three-inch barrel since the rising barrel is carrying it upward during recoil longer before it exits the barrel. Again, I am not arguing the point of greater accuracy with a longer barrel. This is, however, an example of where insomnia can leave you. I would appreciate your thoughts. Link to comment Share on other sites More sharing options...
Hi-Power Jack Posted October 21, 2012 Share Posted October 21, 2012 1. a longer sight radius on a pistol enhances accuracy. 2. the round fired from a six-inch barrel should be expected to land higher than one from the three-inch barrel since the rising barrel is carrying it upward during recoil longer before it exits the barrel. Interesting points, but: 1. imagine the front & rear sight being one inch apart - if you're off by 0.01", that's twelve MOA more than if the sights are 12 inches apart, and you're off by 0.01" - the longer sight radius enhances precision - not accuracy. 2. the bullets may be landing higher, but if you hold the gun consistently, the bullets should land together - doesn't disrupt precision - just requires a more uniform grip. Just my guess - let's see if anyone knows the correct answer Hope you sleep well tonight Link to comment Share on other sites More sharing options...
warpspeed Posted October 22, 2012 Share Posted October 22, 2012 Think about how a one inch group at 100 yds opens up to two inches at 200 yds. A one inch group at 200 is more precise than a two inch group, right ? So look at it backwards. The longer sight radius enables you to get more precision by keeping that same one inch but at a greater distance. Link to comment Share on other sites More sharing options...
Guy Neill Posted October 22, 2012 Share Posted October 22, 2012 Longer barrels also normally have higher (taller) front sights to compensate for the longer barrel time of the bullet. Link to comment Share on other sites More sharing options...
DonovanM Posted October 22, 2012 Share Posted October 22, 2012 It's like using a sharper scalpel for me. It doesn't change mechanical accuracy any more than the added barrel length does, it just enhances the availability of precision, because the same relative error in sight alignment in a longer sight radiused gun equals less error in the target in comparison. Whether or not that's really helped me out on one single occasion is unknown. Link to comment Share on other sites More sharing options...
okshootist Posted October 22, 2012 Share Posted October 22, 2012 Cornerpocket, I have come to believe that if you don't reconfigure the relative sight widths, the longer radius is of little or no advantage for the reason you cited. As to recoil, remember that the friction of the bullet traveling through the bore is limiting muzzle rise until it exits and longer barrels typically have more mass. So, it's probably a pretty small factor. However, the additional time the bullet is in the barrel does give you more opportunity to ruin a shot with bad follow-through. Link to comment Share on other sites More sharing options...
TerryT Posted October 22, 2012 Share Posted October 22, 2012 If you could hold the sights perfectly still and aligned on a 3" barrel versus a 6" barrel, the accuracy should be the same. The issue is that with a smaller sight radius, it is harder to tell if there is misalignment. Off 1/64" on a 3" barrel will put your bullet off twice as much as a 6". Link to comment Share on other sites More sharing options...
Mark K Posted October 22, 2012 Share Posted October 22, 2012 About 20 years ago, international smallbore rifle shooters started extending their sight radius about 6" to get more precision in aiming. About the same time, some inventive folks realized that the bullet would be under the shooter control in the barrel for longer (not good), so they shortened the barrels about 10" to the legal limit of 18" (.22lr powder is also already burnt up by then, so no additional velocity to be gained), and put "Bloop Tubes" on the end of the barrel to put the front sight out where they wanted it. Longer than the old barrel length for prone, where you have a more stable position, and somewhat shorter (about the old barrel length)for standing/kneeling where the shooter's movement is greater. The front sight being at the end of a fulcrum that is anchored to the shooter. The longer that radius, the harder it is to control. The point is - longer is more precise, but at some point it is harder to control. The difference in one inch on a pistol, 5-6" is useful, but get very long and it is hard to aim quickly. I have shot a 6" STI for a couple years, and love it, and shoot it better than my older 5" models. Mark K. Link to comment Share on other sites More sharing options...
wgj3 Posted October 22, 2012 Share Posted October 22, 2012 (edited) I think that Mark explained it about as well as it can be explained. I've been running a 6" for a couple months now, and I can tell you that I have a much harder time getting the front sight aligned than I do with my M&P Pro. I think that some of that has to do with the platform change and some has to do with the increased difficulty in precise control. I believe that all of my close-in shots that are mostly point shooting anyway have not changed much, I perceive that my longer range accuracy shooting has improved, and I believe that the middle range stuff is where I see the greatest challenge with the new-to-me pistol. The time I spend aligning my sights seems to have increased a little, so I just quit aiming... It seems that I have read about how a higher magnification scope is great for being able to see your target (allowing for highest degree of precision), but it also amplifies ALL your movement (causing you to over-correct a lot). The longer sight-radius pistol is kinda like that; its all about finding the happy medium of precision vs. control-ability. Anyone seen a 7" yet? (and, I would think that recoil would begin when the projectile ceases to be at rest) Edited October 22, 2012 by wgj3 Link to comment Share on other sites More sharing options...
HotLoad Posted October 22, 2012 Share Posted October 22, 2012 I am also curious how a 7" sight radius would be to align quickly? I am waiting for bench time for a 2013 legal limited gun and have several ideas in my head. One of them being a modified slide with a 7" sight radius. Any thoughts? Jeff Link to comment Share on other sites More sharing options...
outerlimits Posted October 22, 2012 Share Posted October 22, 2012 AMT Hardballer, baby! my 1st 1911. shot the 1984 steel challenge with it...rough. Link to comment Share on other sites More sharing options...
Cornerpocket Posted October 23, 2012 Author Share Posted October 23, 2012 Thanks for the replies. I appreciate the input from all. And I'm sleeping better. Link to comment Share on other sites More sharing options...
MoNsTeR Posted October 23, 2012 Share Posted October 23, 2012 First, the rear sight is at a constant distance from the shooter's eye. In my 686 example, the only difference is that the front sight is 3 inches further away from the shooter's eye on the six-inch model vs. the three-inch model. The shooter should perceive the front sight as narrower given its further distance from his eye. With the rear sight still perceived as the same relative size, it seems that, from the shooter's perspective, he should have the perception of more daylight on either side of the sight which is six inches away and have greater difficulty getting the "smaller" front sight centered in what he perceives as a now relatively "wider" rear notch. (emphasis added) It is true that the same front sight moved farther out will appear smaller. It is not necessarily true that this will make it harder to align. The relationship between the size of the light bars and effective sighting precision is 1) not linear and 2) not the same for all shooters. Link to comment Share on other sites More sharing options...
Got Juice? Posted October 23, 2012 Share Posted October 23, 2012 Don't forget, longer barrels lend themselves better to point shooting. So in purely instinctive shooting they allow you to 'point' more accurately at a target without having to align your sights as precisely. Link to comment Share on other sites More sharing options...
P.E. Kelley Posted October 23, 2012 Share Posted October 23, 2012 AMT Hardballer, baby! my 1st 1911. shot the 1984 steel challenge with it...rough. You are the coolest kid on the block! I wanna play in your gun safe. Link to comment Share on other sites More sharing options...
Sin-ster Posted October 23, 2012 Share Posted October 23, 2012 How much longer does a bullet moving at say... 1000 FPS (for a fairly average non-Open gun figure) dwell in a 6" barrel vs a 5"? I wonder if that "extra time to screw up the shot" is notable, or just a matter of milliseconds? Mathematically, I guess it works out to .00008333? But I was never good at "word" problems... Link to comment Share on other sites More sharing options...
Will_M Posted October 23, 2012 Share Posted October 23, 2012 How much longer does a bullet moving at say... 1000 FPS (for a fairly average non-Open gun figure) dwell in a 6" barrel vs a 5"? I wonder if that "extra time to screw up the shot" is notable, or just a matter of milliseconds? Mathematically, I guess it works out to .00008333? But I was never good at "word" problems... Close, but not quite The 5 inch barrel is 0.00016666 seconds faster. Assuming a muzzle velocity of 1000 fps. Link to comment Share on other sites More sharing options...
HotLoad Posted October 23, 2012 Share Posted October 23, 2012 Yah what the last guy said. Link to comment Share on other sites More sharing options...
Sin-ster Posted October 24, 2012 Share Posted October 24, 2012 (edited) Ha-- my eyes cross looking at that matrix of equations. Math > English? My far more simple equation somehow halved the actual figure. Wonder how that happened? ETA-- You want a real challenge, Will-- figure out how fast I must be moving the gun from the moment of ignition to turn an A into a Miss @ 7 yards with a 5" gun, compared to holding a D with a 4.5"... Edited October 24, 2012 by Sin-ster Link to comment Share on other sites More sharing options...
MattYvip Posted October 24, 2012 Share Posted October 24, 2012 After having used a 5" gun for limited for several years I switched to a 6" for this season. That being said there is a huge difference for me. As stated I'm able to be more precise with the longer gun. I thought I completely missed a few rounds on longer targets at matches only find I actually hit Cs when I thought it was a miss. The recoil impulse is way different. I've experienced almost zero muzzle rise using major power factor ammo. Granted that is just my experience. Somewhat less technical than some of the above posters; but I'm not the smartest dude on the block so, sadly, Math was never my strong point. Link to comment Share on other sites More sharing options...
a matt Posted October 24, 2012 Share Posted October 24, 2012 A GOOD 6" will transition/point like a 5" and is just easier to shoot. tight, or longer targets are a non issue with a 6". IMHO Link to comment Share on other sites More sharing options...
DonovanM Posted October 26, 2012 Share Posted October 26, 2012 How much longer does a bullet moving at say... 1000 FPS (for a fairly average non-Open gun figure) dwell in a 6" barrel vs a 5"? I wonder if that "extra time to screw up the shot" is notable, or just a matter of milliseconds? Mathematically, I guess it works out to .00008333? But I was never good at "word" problems... Close, but not quite The 5 inch barrel is 0.00016666 seconds faster. Assuming a muzzle velocity of 1000 fps. You can do it in one step with d=(vi+vf)/2 * t Link to comment Share on other sites More sharing options...
benos Posted October 26, 2012 Share Posted October 26, 2012 A longer sight radius provides greater accuracy due to less margin of visual error. Extreme example: Say the front sight and the rear sight are only 2" apart. When you ared aiming that setup, the sights will look aligned (and perfectly still) even if they are off by a couple thousands of an inch. Now take a handgun with a 10" sight radius. Those sights will never look still. And even if it looked like the sights were misaligned by .001" when the shot broke, that will still be 5 times more accurate that the 2" sight radius, that looked perfectly aligned even though they were off by a few thousands. be Link to comment Share on other sites More sharing options...
jeep45238 Posted October 28, 2012 Share Posted October 28, 2012 The reason is simple. The further apart the sights are, the easier it is to detect if the sights are not properly aligned. This is the same reason why rifles are more accurate than pistols (not counting major design differences). Put optics into the equation, and then it's no longer in the equation, as the sight radius is identical for both (infinate). This is why it's easy to peg a steel @500m with an SBR, or a iron sight 20"AR. Link to comment Share on other sites More sharing options...
mattwaage Posted October 28, 2012 Share Posted October 28, 2012 Way too much though put into this. Its cuz the muzzle is closer silly! Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now