Uberti 1860 Army front sight

[M. De Land]

Lowering the top would be the opposite of raising the front, but lowering the bottom of the notch - how does that help?

It doesn't, only the top of the rear matters for elevation.

 

[45D]

Lowering the top would be the opposite of raising the front, but lowering the bottom of the notch - how does that help?

Ok. If the tops of the sights are in alignment and the POI is high, your front sight is too short ( or your rear sight notch isn't deep enough). To move the POI down, you hold the front sight lower in the rear sight notch ( "bury" the front sight). If POI is still too high when the front sight is held at the bottom of the rear notch, cutting the rear notch lower gives you more room to " bury the front sight".
Of course the better solution is a taller front sight but until you get that taken care of, "sight regulation" is how that works.

Mike

 

[Rum River]

Lowering the top would be the opposite of raising the front, but lowering the bottom of the notch - how does that help?

Look at it this way:
Your line of sight is an absolute. It never changes as this invisible line from your eye extends through the aligned sights and then to the target.

When you adjust iron sights you are actually moving the firearm around your line of sight.

If the bullet holes are high on the target, lowering the notch on the rear sight pivots the rear of the firearm upward, which in turn angles the bullet trajectory downward.

 

[wiscoaster]

I don't completely understand how filing the notch in the rear sight would help.

Enables holding the top of the front sight blade deeper down in the hammer's v-notch.

 

[Jim in Wisconsin]

I understand the geometry of the sight alignment vs point of impact - but at least for me, burying the front sight in the notch just covers up the target, unless the rear sight would be a real wide shallow "V" (which it isn't on a revolver).
I always line up the tops of the front and rear sights, I suppose other people do it different ways.

 

[wiscoaster]

....
I always line up the tops of the front and rear sights, I suppose other people do it different ways.

No, other sights are intentionally designed to present different sight pictures. At the risk of naming an "unmentionable" here, I'd suggest researching "Carcano" as a prime example.

Come to think of it now, the buckhorn sight on my Pedersoli Frontier is a "mentionable" example.

 

[Siringo]

I used a small jewelers file and widened the notch in the hammer. The front sight has to be 0.21” high from the barrel. Then front sight level with the top of the notch. The front sight groove is a dovetail. Sight is meant to be tapped in forward to aft.

 

[JimCunn]

"If the bullet holes are high on the target, lowering the notch on the rear sight pivots the rear of the firearm upward, which in turn angles the bullet trajectory downward"

I align the TOP of the sights, so this doesn't work for me. Raising the front sight does.

 

[hawkeye2]

Filing the notch deeper will allow one to bury the front sight deeper in the notch but it's a crude solution to the problem. It isn't possible to bury the front sight to the same depth with every shot and no one ever finished in the top at the nationals by doing so. Filing the top of the hammer down after deepening the groove so that the top of the sights are level does work but (IMHO) the answer is to fit a taller front sight.

 

[Rum River]

Lowering the top would be the opposite of raising the front, but lowering the bottom of the notch - how does that help?

Look at it this way:
Your line of sight is an absolute. It never changes as this invisible line from your eye extends through the aligned sights and then to the target.

When you adjust iron sights you are actually moving the firearm around your line of sight.

If the bullet holes are high on the target, lowering the notch on the rear sight pivots the rear of the firearm upward, which in turn angles the bullet trajectory downward.

"If the bullet holes are high on the target, lowering the notch on the rear sight pivots the rear of the firearm upward, which in turn angles the bullet trajectory downward"

I align the TOP of the sights, so this doesn't work for me. Raising the front sight does.

Filing the notch deeper will allow one to bury the front sight deeper in the notch but it's a crude solution to the problem. It isn't possible to bury the front sight to the same depth with every shot and no one ever finished in the top at the nationals by doing so. Filing the top of the hammer down after deepening the groove so that the top of the sights are level does work but (IMHO) the answer is to fit a taller front sight.

I agree the best option is to raise the front sight to lower point of impact on a fixed sight percussion revolver. I currently own a couple of specimens on which I need to exactly that. They happen to shoot so high it would be impossible to file a notch deep enough on the hammer. If it were a matter of inch or two of correction at 25 yards - that's one thing. In my case they're hitting 8"-9" high.

I didn't know 'Jim in Wisconsin' wasn't using the bottom of the hammer notch so in that case filing it deeper would be pointless.

 

[M. De Land]

It doesn't, only the top of the rear matters for elevation.

Burying the front sight in the rear notch for POA change is poor economy for open sight function as the top (rear flat is best) is what allows full , unobstructed sight picture for bullseye target shooting or hunting. It lets in the most light for sight definition , windage and elevation calibration.
A much better set up than burying the front sight in the notch is to use the top flat of the rear with some light either side of the front blade showing through and bars for elevation change on the rear of the front sight. This keeps the calibration for the target on top of both the rear flat and front blade. The front blade is being elevated (raising the bore) as the rear sight top flat crosses the elevation bar on the back of the front sight maintaining the light on either side.
The deeper one buries the front sight in the rear sight notch the more they loose the all important light showing through the rear notch on either side of the front blade and the more the target is obstructed from view !