Rifle shoots high?

[jethro224]

Move the sights up to .750 and move the aim point out to 80 yards and you will see the data says the ball climbs above the line of sight before dropping back to zero at the aim point distance.

...which is most likely almost exactly what would happen if the OP moves his target out there to 80.

 

[jethro224]

In an iron sighted muzzle loader, the point at which the ball may rise above the line of sight is so close to the muzzle as to be meaningless -

Please explain how, in the chart you posted, a ball leaves the muzzle .5" ABOVE the line of sight. Impossible!

 

[Semisane]

...which is most likely almost exactly what would happen if the OP moves his target out there to 80.

:rotf: You've got to be kidding. The OP's sights seem to be set so he's hitting zero at 30 yards. Were he to shoot at an 80 yard target with that same sight setting he will hit somewhere between four and five inches low.

 

[jethro224]

According to the info in your own .490 ballistic tests, your rifle hits a couple inches high at 50, and dead on at 75. Where does it hit at 25? 4-5 inches high? I doubt it.

And I'd still like to know how the ball in your chart on this topic leaves the muzzle higher than the barrel.

 

[Semisane]

Please explain how, in the chart you posted, a ball leaves the muzzle .5" ABOVE the line of sight. Impossible!

You're right Jethro, that is impossible. I transferred the wrong file to Photobucket. Those two + signs should be negative signs. Here's the correct chart.

 

[Semisane]

According to the info in your own .490 ballistic tests, your rifle hits a couple inches high at 50, and dead on at 75. Where does it hit at 25? 4-5 inches high? I doubt it.

And I'd still like to know how the ball in your chart on this topic leaves the muzzle higher than the barrel.

Dang Jethro, you're really giving me a workout. :grin:

As you noted, the ballistic chart you're referring to is based on a 75 yard zero. (http://www.muzzleloadingforum.com/fusionbb/showtopic.php?tid/297011/) I didn't include the trajectory at the 25 yard mark and, of course, it's slightly different for each load/velocity.

Here are two examples.

For the 60 grain load (1356 fps) the ball will be 1.6" high at 25 yards. It will reach it's highest point above the line of sight at about the 45 yard mark. That highest point will be 2.1".

For the 100 grain load (1685 fps) the ball will be 1.2" high at 25 yards. It too will reach it's highest point above the line of sight at about the 45 yard mark. That highest point will be 1.6".

You don't seem to want to believe this stuff, but Physics is Physics.

 

[jethro224]

Dang Jethro, you're really giving me a workout. :grin:

As you noted, the ballistic chart you're referring to is based on a 75 yard zero...

For the 60 grain load (1356 fps) the ball will be 1.6" high at 25 yards. It will reach it's highest point above the line of sight at about the 45 yard mark. That highest point will be 2.1".

And right there you proved what I've been trying to say all along! Your own ball hit higher at 45 yards than at 25 yards.
As I, and others, said the exact amount higher will depend on many variables such as sight height, sight radius, velocity, etc. etc. etc.

You don't seem to want to believe this stuff, but Physics is Physics.

Just what I was thinking. :haha:

 

[coloradoclyde]

I'm making a beer run.....who wants one ? :haha:

 

[Semisane]

And right there you proved what I've been trying to say all along!

Not hardly. :shake:

Your own ball hit higher at 45 yards than at 25 yards.

Yes, BECAUSE the trajectory shown is for a 75 yard zero.

One last time. The ball can be above the line of sight between the muzzle and the zero point, whether that zero point is 30 yards, 100 yards, or 500 yards. However, it can not possibly be above the line of sight beyond the zero point, regardless of whether that zero point is 30 yards, 100 yards, or 500 yards.

So the OP's problem of hitting zero at 30 yards and six inches high at 50 yards with the same sight setting is not possible if the sights are used the same way for both distances. So he's probably sighting differently on the 50 yard target than he did on the 30 yard target.

That said, I hereby give up. :surrender:

 

[smo]

I was always taught that a ball or bullet would be dead or point blank at two separate times . Once as it crosses the line of sight from below the sight plane then when gravity takes over and it re crosses the sight plane on its way down. :stir: :stir: This is going to get good it looks like :wink:

 

[coloradoclyde]

:thumbsup:

 

[jethro224]

That said, I hereby give up.

SO, I win? :haha:

Before you give up, one last thought for you to ponder;

If

The ball can be above the line of sight between the muzzle and the zero point, whether that zero point is 30 yards, 100 yards, or 500 yards.

Just how the heck did it get there without crossing the line of sight? Therefore there are always 2 zero points! The first one is almost always somewhere between 7 and 25 yards.

Now I give up too. :v

Except for one more thing... that ain't 6 inches. Looks more like about 3 or so. Maybe 4.

 

[Semisane]

SO, I win?

Yes, you win. :idunno:

 

[jethro224]

Dang, it was just startin' to get fun.

 

[Semisane]

I was always taught that a ball or bullet would be dead or point blank at two separate times . Once as it crosses the line of sight from below the sight plane then when gravity takes over and it re crosses the sight plane on its way down. :stir: :stir: This is going to get good it looks like :wink:

Well that's generally true smo. But the first crossing of the line of sight is so close to the muzzle as to me virtually meaningless for the purpose of sighting in a rifle (it's about ten yards or less). Unless of course you plan to sight in for very short distances. :grin:

However, it's not always true. Note that in the case of the OP's ballistics, because the zero point is a short 30 yards the ball does not rise above the line of sight. It just reaches it before beginning the drop.

 

[Semisane]

Here's an illustration of the usefulness of that smo.

Let's say I have a 50 caliber gun shooting .490 balls over 85 grains of powder, and I know the muzzle velocity to be around 1575 fps.

If I want to sight the gun in for a 50 yard zero I can use a ballistics calculator and find that the trajectory that hits point of aim at 50 yards will have the ball crossing the line of sight at 8 yards. So I can take a few shots with a very small dot on a target at 8 yards. When I get the sights adjusted so I'm hitting that dot at 8 yards I can expect it to be pretty well on target at 50.

The ball will be slightly above the line of sight between 8 yards and 50 yards (but no more than about a half inch at its highest point), and will begin dropping below the point of aim at the 50 yard mark. Past 50 yards it will continue dropping forever (well, until it hits the ground or something :wink.

Applying the same principle, if I want to sight the gun in for a 75 yard zero I need to place that target with the small dot at 5 yards because the trajectory that hits point of aim at 75 yards will have the ball crossing the line of sight at 5 yards.

 

[longcruise]

Darn, I step away for a few minutes to make popcorn, come back and It's over.

 

[Semisane]

:haha: It ain't over `til Jethro says it's over. :rotf:

 

[Twisted_1in66]

It should be shooting just slightly high at 30-yards, higher yet at 50-yards, and dead on at 100-yards, or wherever the rifle was originally zeroed in at. Usually if you get near 2000 fps, you can get the ball to point of aim at 100 yards and only about 2" to 3" high at 50-yards.

Before you start messing with the sights though, I'd suggest you work on your load a bit more. Typically at 25-yards (or 30-yards in your example), when shooting from a rest you should be looking at an inch group or so. Check your patches to make sure they don't have any cuts in them or burn-through spots and if they don't, then you need to back off a bit on the powder charge and slowly work your way back up again. Start at about 50-grains and work your way up 5-grains at a time until the group is tight. You will want to take 3 to 5-shots with each load before moving on to the next.

Once that group comes back together, continue adding 5-grains at a time until it starts to open up again. Then you will know what the minimum accurate load and maximum accurate load is for that rifle. After you've established those two loads, then start shooting at the 50-yard targets to see where the group goes.

At 50-yards, it should still shoot high, though not as much as your picture. At that point, it depends on whether you want to zero it at 50-yards which will give you in the vicinity of a 7½" of drop at 100-yards; zero at 75 yards with about 4¼" of drop at 100-yards; or dead-on at 100 yards, which will shoot about 3.7" high at 50-yards. So it's all a compromise and the right distance depends upon your hunting conditions.

But get those groups tighter at 25 or 30-yards before you start adjusting or replacing your sights.

Twisted_1in66:thumbsup:
Dan

 

[azmntman]

Yea BUT WHAT IF YER USING 2F? :hmm: :shocked2: :redface: :slap:

Sorry