While on another site, a poster claimed that when he sighted in his 12 ga with foster slugs,

1- he shot a 1" group out to 50 yards

2 - he shot a 4" group out to 100 yards, however, his trajectory remained the same for 50 and 100 yards.

In other words - If he was 2" high at 50 yards, using the same manufacturer slugs he was also 2" high at 100 yards.

I called this feat impossible and asked if he shot off a "solid rest" ?

His response was that it happens all the time while using a solid rest.

Yes, it is possible. The bullet path (trajectory) is a curved line, arcing downward. The line of sight is straight, so it will intersect the curved bullet path at two points.

Draw a picture, it makes this much easier to understand.

Picture this: The gun barrel is horizontal. The line of sight is angled downward slightly. At the muzzle, the line of sight is above the bullet path. At some relatively short distance, the line of sight crosses the bullet path and goes below the path. As the bullet continues to drop, it will again cross the line of sight at a greater distance.

And more info on above example- if 2"
above line of sight at 50 and 100 yds,
the curve of the bullet path would be
about 3" at 75 yds, and come back down to
the line of sight at about 125 yds. It
would be about 3-4" below line of sight at
about 150 yds. All of above depending
on the speed of slug to start with.Ed

A/C guy:

You exactly said what I had known always (with rifle bullets). I had wanted to jump in and say YES, it is not only "possible" -but what happens. I just didn't know how to express what I knew was a fact. (because it seems to contradict notions about gravity and the bullet falling from the moment it leaves the muzzle) I'm sure many other readers of the original post had the same feelings! You have said "what was often thought but n'eer so well expressed"!

Thanks for the replies!
I'm gonna have to bench test this on my own.

I am unconvinced with regard to a foster slug.

quote:

because it seems to contradict notions about gravity and the bullet falling from the moment it leaves the muzzle

It DOESN'T contradict gravity...It IS falling the instant it leaves the barrel. Consider this:

If the barrel was perfectly level, the bullet/slug point of impact will be lower and lower as the distance to the target increases. BUT...when you introduce sights into the equation...(we want to hit something 2" high at 100 yds as an example)...we have to raise the muzzle end to "lob" the bullet into our intended target. On the way there the bullet is rising not because of a contradiction of gravity, but because we raised the muzzle up to lob it into the target. Think of it like throwing a baseball 100+ yds. You have to aim it "up" the first 1/3 of the flight path so that it can fall to where you intended it.

Finally, draw a horizontal imaginary line between you and the 100 yd. target. This is the "line of sight". It doesn't matter if it's a .220 swift bullet, a shotgun slug or cork out of a kids popgun...you have to raise the muzzle up for the bullet to "fall" into the target. And as someone in a post above stated it will be ballpark +2" high at 50 yds...probably +3" or so high at 75 and back to +2" at 100 yds...but only because you raised the muzzle up to get it there.

Hope that helps a little

6.5Gibbs:

I didn't say it contradicts gravity. I said it "seems" to contradict gravity. (Because the original poster thought so) Your mention of the sighting arrangement is our common experience, of course, that lends the illusion that the bullet is not falling from the moment that it leaves the barrel (and it is the barrel's inclination with reference to the earth that has led to this discussion. I should have kept my big mouth shut in the first place!) Regards, anyway -even if you do think I'm an idiot!

Big time OOOPS! Sorry gerrys375. I misread your post. I thought you were still confused and I thought I'd put my .02 in. This is definitely one of those subjects that could be solved with a legal pad, a pencil and about 60 seconds of explaning. Pretty tough though with only a keyboard. Once again...sorry!

PS And no, you're not an idiot...I'm the one that was confused.

PSS I used to teach hunter education classes and this was one of the toughest things to explain to 12 yr. olds...even with a chalkboard! Too many "old wives tails" passed down from their granddads, dads and other assorted experts.

I'm sorry - I don't want to beat a dead horse.

The initial premise:

The shooter holds same elevation at 50yds as he does for 100yds. He shoots 2" high at 50 yds

He does not raise his sights to go 2" high at 100.

Without the "arc of trajectory" - if the bullet leaves the barrel parallel to the ground, the bullet will be lower at 100 yds than at 50yds.

quote:

Originally posted by tarkus:
I'm sorry - I don't want to beat a dead horse.

The initial premise:

The shooter holds same elevation at 50yds as he does for 100yds. He shoots 2" high at 50 yds

He does not raise his sights to go 2" high at 100.

Without the "arc of trajectory" - if the bullet leaves the barrel parallel to the ground, the bullet will be lower at 100 yds than at 50yds.

Yes, BUT.... (there's always that but... )

The guys above did a pretty good explanation.

You seem hung up on "parallel to the ground".

If the barrel was truly level and parallel to the ground, it would be IMPOSSIBLE for the bullet/slug to EVER be above the bore. So the 2" high at 50 yards (or 100) would be a physical impossiblity. It is only possible through inclining the barrel bore up through the line of sight (which IS a straight line as far as you can see).

So, by angling the barrel slightly up, it works.

Look at a rear sight that slides up and down a ramp. There is your incline. The line of sight and the bore are not parallel, they converge.

A common example is the military and M-16s with 5.56mm/223 Rem ammo. If sighted in at 25 yards, they will be pretty close to dead on at 300 yards. Because the bullet passes through the line of sight at approx 25 yards, CONTINUES to "climb" (not because it is anti-gravity, but because it was initially launched "uphill"), tops out at somewhere around 225 yards, then passes back through the line of sight at 300 yards (or meters). This definitely isn't because the 223 is so fast that it is still flat at 300 yards.

Like somebody else said, it is very easy to draw it out on paper, a bit more difficult to explain in words.