Barrel Length And Perceived Lead


Bruce,

I’ve heard some guys say that the longer 30″ barrels allow you to use less perceived lead as compared to the shorter 26 or 28″ barrels. It seems to me the longer barrel would require more perceived lead not less.

Let’s assume the distance from your eye to the end of a 26″ barrel on an 1100 is 37″. You use a perceived lead of 2″ between the sight at the end of the barrel and a 90 deg. crossing target. The angle between your barrel and a straight line to the target is 3 deg. At 63′ a 3 deg. angle will give you 3.3′ of lead.

Now let’s swap in a 30″ barrel. The distance from your eye to the sight is now 41″. With the same 2″ perceived lead, the angle between your barrel and a straight line to the target is now 2.8 deg. At 63′ a 2.8 deg. angle will only give you 3′ of lead.

So it seems you would have to increase the perceived lead with the longer barrel to achieve the same actual lead at the target. Where did I go wrong?

Thanks,
Lee

Dear Lee,

Well, I’ve never really looked at it the way you mention. Most people feel that the longer the barrel, the LESS the perceived lead. I certainly feel that way myself, though I had never bothered to figure out why the same way I never bothered to figure out how gravity worked. It seemed a pretty reliable natural phenomenon, so I let it go at that.

Let’s start from the beginning. If you shoot a premounted gun with a completely flat rib, you will have absolutely no sense of barrel length. It could be two inches or two yards long. It would look the same. This is because the sighting eye looks right down the rib. It is like putting your head right down on the highway like one of those flat armadillos and then trying to judge distance. It doesn’t work.

It’s only when you look OVER the barrel as in a high trap stock shot premounted, or a low gun where the bird is “sighted” while the gun is still slightly off the face, that you get a sense of the barrel length. This means that the master eye is on a slightly different plane than the rib.

So, now that we know that the master eye is not on the same plane as the rib, it’s much easier to appreciate how a long barrel gives the illusion of less lead than a short one.

Hold you hands out in front of you as though your were parting the waters of the Red Sea. Hold them three feet apart. You will actually have to move your eyes to go from your right hand to your left. Now put a yard stick measuring three feet (most yard sticks are three feet) out at the crossing stake of a skeet field. Aim your right hand at the right end of the stick and your left hand at the left end. I’ll bet that your hands are much less than an inch apart. Same three feet, but different distance.

That’s how it works with long barrels and short barrels. Althought the target you are measuring against is, say, 21 yards, the barrel that makes up the other end of the measurement is close in if it’s a short barrel and somewhat further away if it’s a long barrel. Close measurements seem big like when you held your hands out to measure one yard. Far measurements seem smaller like when you measured that 21 yard distant yard stick.

Things that are close just plain seem bigger than things that are far away. The aiming end of short barrels are closer to our eyes than the front beads of long barrels. That means that the same lead appears less for the longer barrels. Has to. Got to. And it works that way.

I’m sure that there are plenty of math types out here who can do the sines and cosines to back me up. My eighth grade algebra teacher is probably spinning in his grave. Heck, I was a bullet-headed jock in college, not a math student. I thought of everything in terms of ten yards at a clip, not in tens as centimeters and centipedes.

But I’m still right. Longer barrels make leads appear shorter. That’s a fact.

Best regards,

Bruce Buck
The Technoid writing for Shotgun Report, LLC
(Often in error. Never in doubt.)

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