Rifle shoots high?

[Semisane]

Nowhere does he say that he was zeroed in at 30 yards.

We don't know what he zeroed in for, or even if he knows what he's zeroed in for.

Take a look at the OP's first target Grumpa. It shows three shots at 30 yards that all hit around the perimeter of a one-inch dot.

It's reasonable to assume the sights are set for a 30 yard zero. At least that's what I based my assumption on.

 

[Semisane]

Semisane,

By your own table, with a 100yd zero, the ball is +2.6" @30yds, and 3.6" @50yds. This is what we've been saying all along. Am I missing some obscure point here?

The reason the trajectory in that table shows the ball +2.6" @30yds, and 3.6" @50yds is because the zero is 100 yards. The 30 yard point and the 50 yard point are between the muzzle and the zero point.

Some of the guys hold the belief that a ball can rise after it passes the zero point. That belief is incorrect. The laws of Physics will not allow it.

It makes no difference whether the zero is 25 yards, 50 yards, 75 yards, 100 yards, or beyond. The ball will be above the line of sight to the zero point and below the line of sight once it passes the zero point. It can't hit higher than the zero point once it passes it.

 

[Semisane]

It makes no difference whether the zero is 25 yards, 50 yards, 75 yards, 100 yards, or beyond. The ball will be above the line of sight to the zero point and below the line of sight once it passes the zero point.

Let me modify and clarify that statement before the nitpickers jump on it.

It makes no difference whether the zero is 25 yards, 50 yards, 75 yards, 100 yards, or beyond. The ball will *rise* [strike]be[/strike] above the line of sight *between the muzzle and* [strike]to[/strike] the zero point and *continue to fall* below the line of sight once it passes the zero point.

 

[Pete G]

The bullet trajectory crosses the line of sight twice; once at the "near zero" when rising and one at the "true zero" while falling.

 

[smo]

That's what I thought we said :hatsoff: :hatsoff: :haha:

 

[Semisane]

The bullet trajectory crosses the line of sight twice; once at the "near zero" when rising and one at the "true zero" while falling.

Not quite Pete. It's once at near muzzle when rising (usually 10 yards or less from the muzzle) and once at true zero.

That's what I thought we said

Again, not quite smo. You said "I sighted in with 80 grns of ffg in my 54 dead on at 25 yards. At 50 it's approx. 4 inches high." (an impossibility).

You guys are going to believe what you want to believe simply because you want to believe it. Then again, perhaps the laws of Physics don't apply on the flat earth on which you live. :hmm: :v

 

[Grumpa]

Either you have confused yourself, or your grasp of ballistics is tenuous.

A ball fired from a rifle will cross the line of sight twice.

Look up external ballistics...near and far zero.

The axis of the bore is not parallel to the line of sight, but angles up from beneath it, so the ball will intersect the line of sight at the near zero, continue "rising"* to its maximum height above the line of sight, then continue falling until it again intersects the line of sight.
Thereafter, the ball will continue to fall until it hits the ground.

* I put rising in quotes, because the ball is falling from the moment it leaves the barrel - which is why the bore has to be angled upwards, relative to the line of sight, in order to have any kind of usable trajectory.

 

[Semisane]

Either you have confused yourself, or your grasp of ballistics is tenuous.

A ball fired from a rifle will cross the line of sight twice.

Look up external ballistics...near and far zero.

Grumpa, Grumpa, Grumpa.... It's your reading comprehension that is tenuous. (Sorry buddy, I couldn't help myself. :grin: )

At no point did I deny that the ball crossed the line of sight twice. In fact, I confirmed that several times in this thread and provided examples.

On 10/16/15 at 8:39 (Post #1518253) I posted the trajectory chart for a 30 yard zero with the OP's guesstimated velocity. That chart - posted again below - shows the ball leaving the muzzle 0.5" below the line of sight, rising to the line of sight at 20 and 30 yards, and beginning its fall below the line of sight as it passes the 30 yard zero point. The reason it rises only to the line of sight - and not above it - is because the zero point is so close to the muzzle (i.e. 30 yards)

The issue being discussed was whether the ball could rise after it passed the 30 yard zero and hit several inches high at 50 yards. The chart shows that is not possible. Nor is it possible to devise any load, sighted in for any distance, that would have the ball be in it's "rising" mode as it crosses the 30 yard mark.

Here's that chart once again.



To further illustrate the point, on 10/17/15 at 6:16 AM (Post #1518309) I said that with the OP's load "the trajectory with a 100 yard zero should be something like that shown in the table below." And I clearly stated that "the ball crosses the line of sight at about 4 yards from the muzzle. It remains above the line of sight (with a maximum rise of about 3.6 inches at about the 50 yard mark) until it hits zero at 100 yards. At 100 yards and beyond it drops below the line of sight." (Please note those are exact quotes.)

And here's that chart with the 100 yard zero.

Yards...Velocity...Drop
0............1750........-0.5
2............1725........-0.3
4............1701.........0.0
6............1670........+0.2
8............1640........+0.5
10...........1618........+0.7
15...........1548........+1.2
20...........1483........+1.7
25...........1424........+2.2
30...........1366........+2.6
35...........1315........+2.9
40...........1265........+3.2
45...........1220........+3.4
50...........1180........+3.6
75...........1042........+3.1
100...........951.........0.0
125...........875........-6.1
150...........810........-15.8
175...........749........-30.1
200...........690........-50.0

How you concluded that I do not understand these basic ballistic principles is beyond me.

 

[Grumpa]

:grin:

Semi, I'm glad that you are smiling, too.

As I said in my earlier post, we don't have enough information in the original post to draw any conclusions. And the OP has made himself scarce! I'm starting to wonder if he was just :stir: :haha:

30 yards and 50 yards seem too close together for near and far zeros. Maybe it was 30 feet? As I recall, for a modern rifle, it's about 25 feet.

It's been a long day, and my head is starting to spin. I'm goin' to bed.

PS: Looking at the targets you posted on another thread about ballistics...you sure can shoot well enough! :grin:

 

[M. De Land]

My best match load is 65 grains of 3F in a GM barreled underhammer with a .445 ball.
Often times when a barrel comes and is bored off center it is orientated to point the curve vertically rather than horizontally so the sights will not have to be set way opposite from each other to hit center side to side.
It is much easier to compensate for it on the vertical.
My guess is your barrels bore was deep hole bored on a curve and orientated vertically.

 

[George]

You are correct on all counts, Semisane. I don't have any idea what is happening with the OP's shooting, but your description of the ballistics involved, what's possible and not, is dead center.

Spence

 

[Semisane]

Thank you Spence. I was kinda feeling line the Lone Ranger here. :wink:

 

[George]

I know the feeling.

You did well. What is it they say, A prophet is not without honor save in his own country. It's hard to make headway about ballistics in this crowd. :haha:

Spence

 

[M. De Land]

And then of course there is always the false prophet that must be considered although in this case I think he has it right as far as trajectory is concerned.
I have seen a number of barrel blanks over 35 years of gun building and repair that have been either bored on an angle or curve with the latter being most prevalent.
The bore will look like a jump rope when looked through while spinning slowly in a lathe headstock spindle.
Very often the bore will be centered on each end and have a curve on it in between.
They can still be accurate but must be orientated vertically as they will often deflect their projectile on the same curve as the bore is.
All trajectory charts presume a straight bore in relation to line of sight.

 

[George]

That still won't make a rifle that is actually sighted in for 30 yards shoot high at 50. Once the ball leaves the bore, all the regular laws of physics apply.

Spence

 

[Semisane]

That still won't make a rifle that is actually sighted in for 30 yards shoot high at 50. Once the ball leaves the bore, all the regular laws of physics apply.

Spence

BINGO!

 

[M. De Land]

Ah.............. yes it can, if the bore is curved as I speculate it might be.
Other possibilities are a canted crown angle or even a slightly bent barrel although I would guess the bore having a curve a more likely cause.

 

[George]

Curved bores don't shoot curved trajectories. Once the ball leaves the muzzle, it travels just as though it has come from a straight bore. Only Hopalong Cassidy could shoot around curves. :grin:

If you whirl a stone on a string, and the string breaks, the stone flies straight away, it doesn't curve. Ask Goliath.

Spence

 

[Semisane]

Oh lordy! Here we go again. :rotf:

 

[M. De Land]

It's the angle of departure that is changed in a curved bore, gravity is the constant.
The projectile will still pass through the line of sight at two points just not the same place as a chart that is calculated with a straight line of departure.
Think of a ramped aircraft carrier or ski jump with a ramp as opposed to either with level exit.
The line of departure in either will dramatically effect the trajectory path.