Shoots excellent but LOW

[R.M.]

A higher velocity projectile will suffer from the effects of recoil in the barrel for a shorter length of time.

 

[krecords]

I was shooting low so I filed my front sight as well, only didn't reduce it's height I filed it so I could consistently raise the front sight higher as measured against the rear.
I posted drawings in another thread Here

I shoot pretty consistently with this configuration.
Kirby

 

[Capt. Fred]

QUOTE "A faster projectile will always shoot lower. I've witnessed it many times. It has nothing to do with drop."

Mark, if this is the case please explain. Why does this happen? I could see it being true in some rifles due to a quirk with that particular gun or shooter but my knowledge about such things would indicate that something else is going on if this is occuring. Something that should be corrected if possible. Is it due to barrel whip or something? You say it will ALWAYS shoot lower with more powder. How come?

 

[MikeChapin]

..
Mark, if this is the case please explain. Why does this happen? I could see it being true in some rifles due to a quirk with that particular gun or shooter but my knowledge about such things would indicate that something else is going on if this is occuring. Something that should be corrected if possible. Is it due to barrel whip or something? You say it will ALWAYS shoot lower with more powder. How come?

I know you addressed this to Mark but maybe I can answer it.

The force of gravity works by making the ball drop at a uniform rate. How much drop you are going to get is related to how fast the ball is moving. If the ball crosses the distance faster it will drop less than a ball crossing the same distance at a slower speed.

It sounds like I just refuted myself. If the rifle is setting flat this will indeed be the case but we are not shooting with the barrel flat. The sights cant the barrel up a little so we can impact where the sights are setting rather than shooting low all the time.

If a rifle is sighted in for 100 yards the ball will fly in an arc rising until it hits about 60 yards or so then it will start to fall and hopefully land in the 10x ring. At 25 yards the ball is still rising. With faster velocities the ball will shoot a little flatter and take less time to cross the 25 yard distance so will not rise as much as a slower ball. With a faster ball the high point of the arc will move out a little.

A faster ball will not rise as much as a slower ball because the time needed to get to 25 yards is less and is on a lower part of the arc.

I hope that made sense.

To get back to Kentuckwindage's question, a .58 is a slower moving ball and will show a more pronounced trajectory. I shoot a lot of competition and use two loads. With my .58 I use 60 grains for 25 and 50 yards and 85 grains for a 100 yard and hunting load. These two loads let me shoot at those ranges using the same sight picture. You ought to try shooting that load at 100 yards. You may find the it is pretty close at that range.

 

[rafterob]

Here is my theory on Mark's observations. Higher powder charges give a flatter trajectory at the shorter distances. If you are using a lower charge, then your short distance shots will be hitting the target at a higher arc than a higher velocity shot. If your sights are set for lower powder charges (higher arc) then I could see a flatter trajectory resulting in a lower point of impact at shorter distances. Just a different way of saying what was just said above.

 

[Capt. Fred]

Mike, thanks for that explanation. So, if I understand the example, what you are saying is that the ball is still going up towards the top of its arc when it is hitting low at 25 yds and that makes sense but why does it hit 3" lower at 58 yards? I don't know squat about BP ballistics yet but is it possible that it has already hit the top of the arc and then dropped an additional 3 inches below the 25yd POI all in just 33 more yds?

Kentuckywindage, I just had a thought. Would it be possible for you to reinstall the original sights and measure the distance above the barrel of both of them. Then see what the difference between them is. Could you then copy the DIFFERENCE with the new sights?

 

[musketman]

I know these BP guns can be quirky but isn't it true that, all other things being equal, the faster a projectile is moving the less it will drop over a given distance.

That's what I thought too, the faster a projectile goes, the less time gravity has to pull it downward.

 

[slowpokebr549]

That is what I was always told about this subject. When shooting pistols the effect is really pronounced. A low velocity bullet will always impact higher than a higher velocity bullet of the same caliber and weight given an identical sight setting. The slower round has more time in the barrel, thus throwing the muzzle higher in the time the slug is in the barrel. The faster round has left the barrel sooner and has less time in the barrel to be torqued upward by the pistols recoil. My brother the engineer sought to prove this on paper to me once but the mathmatics of it just made my eyes cross. It seems a little counter intuitive to me, but I have seen it myself while firing LOTS of .38 specials v .357. I hope that makes sense.

 

[paulvallandigham]

My thoughts about this man's problems:

First with 100 grains of any powder, you need a fire wall between the powder and your PRB. I suspect that he is not getting the sealing he needs if he is just using a Patch around his ball in his rifle. He needs to use an OP wad, or a good filler, to seal the gases and get the most use out of that powder charge. And, he needs to be picking up everyone of those patches he fires without the OP wad or filler, to check them for holes, and burning.

I know that with my .50 caliber rifle, which I shot for years with 96 grains of FFg behind a lubed PRB, when I added an OP wad, the POI at 50 yards went up an full inch! My patches have always looked good, but they looked even better after I fired those loads with an OP wads behind them.

Second, the poster doesn't tell us what sight picture he is using. If he is putting the top of the front sight level with the top of his rear sight ears-those right next to the notch -- then he should have had enough play to lower the front sight and raise his POI.

If he is holding a " Fine Bead", where he puts just a hint of the top of the sight in the bottom of his notch, then he's going to be shooting low until he files most of that front sight OFF!( He says he can't file the rear sight notch any lower, indicating that its fairly close to the top flat of the barrel.)

I have my own doubts that the barrel is bent, or that there is anything wrong with its muzzle crown. The consistency of his reported hit locations suggests otherwise.

It would be helpful to know what the MV on these loads are, and the SDV of the loads are for a string of his shots. The SDV would be a good clue to the need for the OP wad or filler. And a jump in the MV when the OP wad is used is to be expected as well. I saw a 25% increase in MV in my 20 ga. fowler when I used the OP wads in my barrel. And the POI rose about 6 inches at 25 yards.

 

[Kentuckywindage]

 

[Capt. Fred]

I think we are overthinking this one. If it shot fine with the old sights at this load then you just need to: file even more off of the front sight, or you need a taller rear sight, or you need to fiddle with your sight picture as Paul suggested.

 

[Russ T Frizzen]

I think I'd just put the old sights back on. They are just basic old-fashioned sights--nothing cheap about them. Best of all, they worked! :thumbsup:

 

[Kentuckywindage]

they just arent as clear as these. Plus the sight i put on looks great. I'll figure something out.

 

[jtmattison]

I see the problem now. SQUARE PATCHES.

:rotf:

Just kidding!

:v

HD

 

[paulvallandigham]

The top two patches suggest that you could stand a slightly thicker patching. At least you are not seeing burning in the centers. The bottom patch, perhaps because of lighting, seems to be less burned around the "ring" that surrounds the middle. I am concerned by the length of the fingers of black residue extending out from the rings in the top two patches. Those are indications of blow-by.

I still recommend you try using a OP wad, or filler, to help seal those gases on that large caliber ball. Remember that RS burns at a much higher temperature than does BP.

 

[Kentuckywindage]

i'll cut some bigger patches. these are actually for my .54 but i used them because it takes a little while for the elk tallow to melt out of the bottle. I'll consentrate on the sights first. As of now if i had the sights working, this baby would be ready to hunt with.

 

[D Sanders]

True...
That is why a the point of impact raises!

 

[renovato]

A higher velocity projectile will suffer from the effects of recoil in the barrel for a shorter length of time.

It's especially noticeable in handguns where heavier bullets, even at lower velocities print higher.

Recoil begins at the moment of ignition. The longer the projectile dwells in the bore, and the more recoil momentum it imparts, the higher the muzzle is pointing when it exits.

 

[shooyer_250]

Windage,,,you say the old sights aren't as clear as these...Sir, May i suggest...if the sights are too bright,,,blacken the sight,,,if they are to dark, white out or a white ink pen will lighten them up...if the problem is (C) none of the above,,,just forget i said anything except goodluck, i hope you get it worked out soon...Lee

 

[Kentuckywindage]

the rear sight is fuzzy with my eye sight so thats why i changed them out. Have the same problem with my cabelas hawken which will get fiber optics.