Trouble with 100 yard zero

[FRJ]

Here are the parameters. 45 cal flintlock with 42" barrel. Load 70 gr of 3F powder. Primed with 4F powder. .445" round ball patched with .015" pillow ticking. Shooting is done off a bench using Caldwell front and rear rests. I have over 50+ years of shooting experience with many hundreds of guns and rifles. The rifle prints one ragged hole in the center of the bull at 30 yards at 60 yards its 6" high and centered with a group size of 1.0" at 100 yards I cant hit the paper. I've held 6" high and 6" low and it doesn't show on the target or the box its stapled to. I have never run into this before any suggestions? FRJ

 

[lonehunter]

I shoot the same load in my .45, It is dead on at 50 yards and only 2 1/4" low at 100. :idunno:

 

[BrownBear]

Wow, 6" high at 60 tells me you're likely waaaay high at 100. My 50 for example, is an inch high at 50 yards when sighted in dead on at 75, and only 3" or so low at 100. Dunno how fast your rifle or mine are shooting, but I'm only using 80 grains of 3f in my 50 cal to get that trajectory. Stand another box on top of the one you're using and see what you get.

 

[jethro224]

Really BIG box.

 

[Dphar]

Here are the parameters. 45 cal flintlock with 42" barrel. Load 70 gr of 3F powder. Primed with 4F powder. .445" round ball patched with .015" pillow ticking. Shooting is done off a bench using Caldwell front and rear rests. I have over 50+ years of shooting experience with many hundreds of guns and rifles. The rifle prints one ragged hole in the center of the bull at 30 yards at 60 yards its 6" high and centered with a group size of 1.0" at 100 yards I cant hit the paper. I've held 6" high and 6" low and it doesn't show on the target or the box its stapled to. I have never run into this before any suggestions? FRJ

Try holding a foot low. 6" high at 60 yards is pretty high if you are getting about 1900 as you should be or very close.

I just ran it at a BC of .065 at 1900 and 6" high at 60 makes for 6"+ at 100 more if the sights are high or the velocity is higher
How high is it at 30 yards? I suspect its over 3".
I would zero this thing to place the ball 1.25" high 25 yards. Unless the sights are very high this will put you close to "on" at 100.

Dan

 

[Stumpkiller]

With my .54 I'm about 1-1/2" high at 50 yards, on at 85 yards and about 3" low at 100 yards . . . but by then it's a 6" scatter. That's with a load of FFFg in a flintlock. Maybe 1,600 fps at the muzzle. :idunno:

 

[FRJ]

I'm using a 6 oclock hold on a 2" bull and hitting exactly dead center. That would be 1" high at 30 yards. 6" high at 60 yards may mean as others say that its really high at 100. I'll try the large backer as already suggested and get back here and report. In the past however if I was on at 25 a rifle would be close to on at 100. Wish me luck. FRJ

 

[Rifleman1776]

I don't believe a 25 or 30 yard target will give any useful information.
The 60 yard one is a good indicator though.
As suggested, hold low and look for point of impact. If possible, attach a very large hunk of paper behind the target. You really mustfind out where that ball is going before you can make adjustment. I have used cardboard from appliance shipping boxes. Big, free and can be disposed of by burning.

 

[cynthialee]

I started with a piece of plywood that is 8'x4'. Plenty big enough to show me where I am shooting. The plywood was just sitting there and I figured it needed some holes in it.
:grin:

 

[Dphar]

I'm using a 6 oclock hold on a 2" bull and hitting exactly dead center. That would be 1" high at 30 yards. 6" high at 60 yards may mean as others say that its really high at 100. I'll try the large backer as already suggested and get back here and report. In the past however if I was on at 25 a rifle would be close to on at 100. Wish me luck. FRJ

You have a problem.
Like maybe a bent barrel.
Otherwise your rifle is defying the laws of physics.

This may not be exactly right but should be very close.

Dan

 

[Stumpkiller]

Hey, cool! Dan's chart agrees pretty closely with my .54. I'm certain I'm three hundred fps +/- slower at the muzzle, but 100 grains of lead heavier so it carries better, and 1.5" high at 50 yards, so being 3" low at 100 yards figures about right.

Thanks Dan. :hatsoff:

PS - 25 yards tells you a lot. 75 yards tells you much, much more. If you're not in a 2" hole at 25 yards with any shoulder arm from a reasonable rest you should stick there until you are and work on technique and load. Then start filing the sights to get you up into the bullseye.

 

[Leatherbark]

I would say your sights are regulated to where the ball is rising in trajectory at 30 yards even though its hitting center. Probably still rising at 100 yards. You are overshooting is my guess. Hold low next time and see where she hits. My 45 GM barrel shot dead on at 125 yards and I had to hold 6 oclock on the belly of the sillouhette pigs at 100 yards, but was only 2 inchs high at 50, but it was still rising in trajectory. I used 70 gr of 3f at the time.

Bob

 

[jerrywh]

Go down to 65 grs. and try it.

 

[Rifleman1776]

Dan's chart agrees with my findings over many years. And that of others I know.
The ideal I try for is: hold center at 25 yards; hold 6'clock at 50 yards; hold center at 100 yards. With optimum load, and holding yer mouth right, all three shots should cut the 'X'.
Zeroed for 100 yards, the ball is still rising at 50.

 

[piteruu]

What is the height of front sight and rear sight in yours rifles and what is distance between them?

 

[FRJ]

Right at the moment I don't know the height of the sights. I have to go in monday for a knee replacement so I wont get back to this till after I've recovered. Probably a month or more. I'll post on what I find soon as that happens. FRJ

 

[piteruu]

I have .45 GM barrel 7/8x42. At 55 yards I use .445 ball, .018 patch (ballistol/water 1/6)and 55gr 3F. At this distance my rifle is sighted to shoot about 2" high. At 110 yards and load 62gr 3F it shoot about 4" low. I think it might be correct but next time I will use 70-75gr 3F. But I don't understand why my rear sight must be 0.16" higher than front sight (sight radius is 29.5").

 

[flintriflesmith]

... But I don't understand why my rear sight must be 0.16" higher than front sight (sight radius is 29.5").

On a straight sided barrel the rear sight has to be taller than the front (taller means farther above the center line of the bore) so that the ball is launched at a slight upward angle. The ball begins to drop the instant it leaves the muzzle and, if the line of sight and the bore were parallel, the ball would never cross the line of sight. What really happens is the ball crosses the line of aim twice: once a few feet from the muzzle and again at the zeroed range.

Although it is about modern bullets the diagram on the Hornady web site shows this fairly well.
external ballistics

 

[piteruu]

On a straight sided barrel the rear sight has to be taller than the front...

This is obvious to me, but 0.16" is rather too much. Don't you think?

 

[flintriflesmith]

On a straight sided barrel the rear sight has to be taller than the front...

This is obvious to me, but 0.16" is rather too much. Don't you think?

Depends on the velocity of your load and the range where you want it to hit dead center. A round ball's trajectory in not wonderful even at with the heaviest loads.