Shooting high

[French Colonial]

Distance between sights in inches X distance to move POI divided by yardage to the target

Example
29"(distance between the sights) X 6"(Point of impact adjustment needed) / 3600" (at 100 yards) = .0483333

37" X 1" / 1800" = .0205555

20" X 1" / 900" = .0222222

25 yards 900 inches
50 yards 1800 inches
100 yards 3600 inches

When getting serious about filing the sights I take a small portable vise with rubber jaws to the range to hold the gun, along with some files, a brass punch for drifting the sights left to right and a pair of digital calipers. I have a hard time eyeballing .0205555 without calipers.

You should not be adjusting the sights at all until you have developed a load for that particular gun that gives you what you believe is the tightest group you will achieve, then adjust the group POI for the range you desire the greatest accuracy.

 

[TreeMan]

I have three 54 rifles with a slow twist. Harpers ferry, Great Plains and a Mortimer. None of them shoot well with less that 65 grains of 3F or 80 grains of 2F. All three of mine group best with 2F.

 

[doubleset]

Distance between sights in inches X distance to move POI divided by yardage to the target

Example
29"(distance between the sights) X 6"(Point of impact adjustment needed) / 3600" (at 100 yards) = .0483333 ...

Okay, I get it. So this is an estimate of how much you'll need to change the sight height based purely on geometry -- and doesn't include bullet drop at that distance based on projectile velocity. Nor does it take into account the height of the sights above the bore. And of course, it can't be expected to give you an answer to, for example, how high a given front sight should be for a given rear sight -- e.g., in the case that you're replacing sights on your gun. But for adjusting an existing sight, it should work just fine.

Since a difference of 200 fps muzzle velocity by itself can make a difference of the desired sight height of about .025" at 100 yds (if my calculations are correct), this is why using this approach makes it critical (as was emphasized) to FIRST DEVELOP THE LOAD YOU WILL BE USING, and also to do the adjustment AT THE DISTANCE YOU WILL BE PLANNING TO SHOOT (at least, the distance you'll be thinking of as your most common or "base" distance).

 

[Daveboone]

With my new Pedersoli GPR (.54) last spring, I had the same problem. Hitting way high., but grouping well. I adjusted the load a bit for group size, then went to Track of the Wolf and bought the highest German Silver blade they had ( I think .310 high). I now had plenty of adjustment range, with the back sight ramp set mid way dead on at six oclock hold at 25, up only an inch or two for fifty. Beyond that I am shooting gongs, and didnt get too fancy with the sighting. I shoot 80 grains FF.

 

[doubleset]

... Track of the Wolf and bought the highest German Silver blade they had ( I think .310 high).

That's the front sight I got for my Crockett rifle to use in making a fiber optic "bead" sight for it. I would have got the shorter one, but it hasn't been available. The base fit my dovetail perfectly!! And I did spend quite an effort with a file on it!

 

[French Colonial]

Okay, I get it. So this is an estimate of how much you'll need to change the sight height based purely on geometry -- and doesn't include bullet drop at that distance based on projectile velocity. Nor does it take into account the height of the sights above the bore. And of course, it can't be expected to give you an answer to, for example, how high a given front sight should be for a given rear sight -- e.g., in the case that you're replacing sights on your gun. But for adjusting an existing sight, it should work just fine.

Since a difference of 200 fps muzzle velocity by itself can make a difference of the desired sight height of about .025" at 100 yds (if my calculations are correct), this is why using this approach makes it critical (as was emphasized) to FIRST DEVELOP THE LOAD YOU WILL BE USING, and also to do the adjustment AT THE DISTANCE YOU WILL BE PLANNING TO SHOOT (at least, the distance you'll be thinking of as your most common or "base" distance).

One, This formula is not an estimate it is very accurate, any sloppiness in your measuring or filing will be the only thing not accurate.

Two, I have never had any luck varying powder charges for different distances, in my humble experience over about 50 years of doing BP I find that there is one load that is "best" for a particular rifle and I develop that load and that is it. My Jaeger load has not changed in decades. (Oldest flintlock I still own).

Three, I do not own any new fangled percussion rifles with adjustable sights, only flintlocks with fixed sights so there will always be some filing and you can only file to a fixed yardage, all other distances must be compensated for in some manner.

 

[doubleset]

One, This formula is not an estimate it is very accurate, any sloppiness in your measuring or filing will be the only thing not accurate.

Actually, I've taken a second look at this, and I think you're right since it's relative impact that's the issue in this model. I need to think about it a little more.

 

[French Colonial]

The geometry is not an estimate. But it is an estimate in not taking account of the physics of the projectile path. If you think about it for a moment, you will see that this approach models the path of the projectile as a straight line while in fact it is a parabola. If your view is that the physics of the situation have no effect on the path of the ball (and so the point of impact), I invite you to please show how this is not the case. I'm not saying that there's anything at all wrong with following the procedure you recommend under the constraints you impose on it. But the calculation of point of impact it models is definitely not precise. That's all. If you insist this isn't the case, then I invite you to prove (using the standard equaions of Newtonian mechanics) that your approach will produce the same results as using the laws of physics for ballistic projectiles -- not that, as a practical matter, this should deter anyone from using the procedure you recommend. None of this is intended as a criticism of your approach.

Bulls**t professor, I don’t need to prove you wrong you need to prove me wrong.

the parabola does not change for a fixed load, it remains constant, any temperature or other physical changes are negligible at the distances we are shooting

I don’t think the cariolis effect is going to be a factor either.

I stick by my formula

 

[Stub]

I have three 54 rifles with a slow twist. Harpers ferry, Great Plains and a Mortimer. None of them shoot well with less that 65 grains of 3F or 80 grains of 2F. All three of mine group best with 2F.

I love to read the postings you folks are giving me to help. I mill over the math but it makes me a little dizzy. I am an old boy who grow up going to school in an old one room school out in the country. During my early years I majored in noon hour and recess.
Using real black powder, resting the gun on my hand, using higher powder charges and such advice, makes sense to me.

 

[French Colonial]

I love to read the postings you folks are giving me to help. I mill over the math but it makes me a little dizzy. I am an old boy who grow up going to school in an old one room school out in the country. During my early years I majored in noon hour and recess.
Using real black powder, resting the gun on my hand, using higher powder charges and such advice, makes sense to me.

do you know how far from your poa the bullet is hitting, I have given you the distance numbers all you need is the distance between your sights

a third grader in primary school can do this

 

[doubleset]

Bulls**t professor, I don’t need to prove you wrong you need to prove me wrong.

Easy, there, old timer.

the parabola does not change for a fixed load, it remains constant,

The general formula for the parabola doesn't change. But the specific parabola -- for a fixed load -- does change as you adjust front sight height because the angle of the bore relative to the straight line to the target changes: more importantly, because this results in a change in the effect of the (downward) gravity vector on the path. Higher angle (from horizontal): less effect of gravity on the horizontal component of the path; lower angle: greater effect of gravity. Basic physics and vector geometry. You can actually see these effects if you run a few examples through the ballistic calculator I gave the link to.

My guess is that you know what's involved in altering your point of aim when shooting uphill or downhill as opposed to more or less horizontally. The physics -- not the geometry -- is what makes this necessary. Consider the limiting cases of (1) a horizontal barrel and (2) a vertical barrel. Two quite different parabolas there (the second is a degenerate one into a straight line if things like rotation of the earth are ignored).

So not exactly "Bulls**t".

You can believe what you like about this. As I've said, the procedure you recommend is a good one on practical grounds, and I think it's a simple and clever approach. You don't have to get the physics exactly right. And you don't really need to feel insulted either. But you can if you want to.

 

[Stub]

do you know how far from your poa the bullet is hitting, I have given you the distance numbers all you need is the distance between your sights

a third grader in primary school can do this

22.5 (distance between sights)x 7 ( point of impact adjustments needed) \ 1800 (@ 50 yards) =.0875
Original front sight was .50 high the new sight is .57 high=.07 higher
So, I am .0175 short of enough height to get on zero at 50 yards. Therefore, I will shoot a short distance high at 50 yards.
I assume that if I hold the fore stock with my hand, increase my powder charge the poi will change some. If I am wrong I am sure someone will correct me,

 

[Stub]

I forgot to say that the bead on the new sight is smaller than the original. That will probably also be a factor.

 

[Grimord]

OP, try this site for round ball ballistics.
Round Ball Ballistics Calculator for Muzzleloaders

 

[French Colonial]

OK professor, When filing the front sight down .020555 for a 6" change, sights 37" apart and 100 yards distance, please use your argument and show the formula and tell me how much the parabolic curve being shifted up will change the point of impact.

I contend in is miniscule and irrelevant, prove me wrong.

 

[French Colonial]

22.5 (distance between sights)x 7 ( point of impact adjustments needed) \ 1800 (@ 50 yards) =.0875
Original front sight was .50 high the new sight is .57 high=.07 higher
So, I am .0175 short of enough height to get on zero at 50 yards. Therefore, I will shoot a short distance high at 50 yards.
I assume that if I hold the fore stock with my hand, increase my powder charge the poi will change some. If I am wrong I am sure someone will correct me,

Your going to be 1.4 inches high on the target, this may be a good sight setting for you if you also plan on shooting longer distances.

 

[centershot]

Stub, lots of guys here, myself included, prefer to use black powder rather than BP substitutes. However, there's nothing wrong with using T7! I've burned a bunch of it in the past and found it to be an excellent powder! It produced good groups, shot clean, was available in most gun shops and was easy to clean at days end - you really can't ask for more! Over time I found that real BP was a tudge more accurate (in MY rifle) and BP doesn't care how long ago you opened the can, it goes "BANG" every time, with proper storage. You can't say that about the subs, not even T&. Over time they lose some potency. Black powder doesn't. A friend of mine who passed away 6 years ago gave me a can of DuPont BP about a month before he passed. I use that powder ONLY to hunt with. DuPont hasn't sold powder in, how long?? BP has incredible shelf life! That's why I came back to it. Yes, it's a pain in the butt to get it but when you buy it, at least, in 10 lb. lots you'll get it cheaper than T7 ever was. Use T7 if you want to, just don't let it sit around for 2 or 3 years after you open it!

 

[doubleset]

I contend in is miniscule and irrelevant, prove me wrong.

I'm good with your acknowledgement of this. I in fact said nothing different. You only got irritated because I pointed out it was an approximation -- which we now appear to agree it is. I won't get into debating your understanding of "miniscule" and "irrelevant," or in what cases that may matter. If you're still unhappy, you'll have to continue down that path on your own.

 

[doubleset]

OP, try this site for round ball ballistics.
Round Ball Ballistics Calculator for Muzzleloaders

Yeah, that's a good one on my list. It takes account of all the relevant geometric and physical issues. Especially useful when replacing sights.

 

[azmntman]

Get different powders (pyrodex, Trilpe 7, REAL black, get different grades (ffg fffg), try MANY different lubes. RUN A CHORE BOY up/down the barrel 40-50-times or shoot 100+ rounds. Find the MOST ACCURATE load from the above and THEN DEAL WITH THE SIGHTS. Other wise we will hear you have a great thing goin on then in 1 year when you have BROKEN IN the Barrel you will be back wondering what's next? Just my.002$

Remember all guns have their load. Even two different rifles with consecutive serial #'s will prefer a different lube, powder charge and/or even caps. You get to play a loooong time to get bessie dialed in. The you start over with another gun!