sighting in frustrations

[Justin Urbantas]

So, I'm trying to get one of my rifles sighted in from the bench, and it's driving me crazy.
It's a .45 flintlock with standard iron sights.
I tapped the rear sight to the right so it hit dead on at 50 yards. I move to 100 yards, and the shots were now hitting 8" to the left (in a fantastic 1" group though, that I added as a picture. Probably the best 100 yard group I've ever fired)
So, now I tap the sight back so it's dead on at 100 yards, and think that should do it.
I fire a group at 50 yards, and now it's 2 1/2" right at 50 yards.
What's going on here? Any suggestions are welcome

[T*O*F]

It can only be the sun messing with your front sight picture.

[Frank]

Your barrel has some run out.

[Justin Urbantas]

Anything I can do to compensate for runout?

[Frank]

Anything I can do to compensate for runout?

This was a common problem in the old Douglas barrels. The solution was to fit the breech plug so that any run out was vertical.  In a barrel that has a breech plug fitted, barrel lugs and sights installed, there is no easy fix.

[rich pierce]

Frank said it all. I guess one could consider bending the barrel sideways. It takes very little and the stock might accommodate it easily.

[Seth Isaacson]

Wouldn't it be simplest to just adjust the sights for 100 yards and adjust your hold slightly for 50?

[flinchrocket]

I would make some cheap shaders from a paper towel tube just to be sure it’s not the sun messing with you.

[MuskratMike]

Here are the shades I make. They may not be historically correct but look the part on my old flintlocks. Go to any hardware store or plumbing supply and buy copper couplings. I use 1-inch ones for my smaller barrels. Cut a section out smooth the sharp edges off and viola shades that work and look good. When you first make them they will be way too shiny but as you can see over time the copper will tarnish and have that old patina we all like.

[Semisane]

Are you sure you're not canting the gun a bit, rather than holding perfectly vertical?

[bob in the woods]

I know that you can shoot, so I'm going with some run out or perhaps a slight "wow" in the barrel.  It doesn't take much. 

[alacran]

Horizontal run out can be compensated for with sights. A straight bore will not do what yours is doing. As Bob says it doesn't take much.
One of the best cross sticks rifle I had had the rear sight way to the left on the dovetail, and the front sight was way to the right.
It did not shoot curve balls like yours is doing.

[Dphariss]

Anything I can do to compensate for runout?

If it were run out it would shoot to one side at all ranges. I.E if it were runout and it was 2”  right or left at 50 it would be 4” out the same direction at 100 If its on windage wise at 100 it should be on at 50. HOWEVER. It takes a surprisingly little wind to drift a ball an inch or 2 at even 50 yards.
Finally light on the sights can be a real hair puller. Try taking a paper tube like one from a roll of TP or paper towel and tape it on to shade the front sight and see what happens. Or maybe BOTH sights.



If it WERE runout or a bore that is not straight through the blank, has a curve but centered at each end. Then the only fix is bending the barrel. Which is common practice as the photo below shows and it was an optical process by someone who knew how. Just BE SURE its not some other “thing”” before bending the barrel.

[D. Taylor Sapergia]

Justin, what charge/patch/ball are you using.  I took know that you can shoot, but I also know you favour very light loads, at times.  I have a pistol that likes 30 gr. 3Fg but I have to aim at the bottom right hand corner of a playing card at 20 yards to punch the Ace out of the centre.  My brother suggested to me to use 35 gr. and now the pistol shoots exactly to the sights.

[Justin Urbantas]

I could try a few more tests before I bend the barrel.  Taylor, I was shooting 50 gr fffg with a .440 ball and .018 patch.

[RAT]

Justin... send Bill (our guild president) an email about the experience he had. He had the same problem with a Rice barrel in his southern mountain rifle. He sent the barrel back and they replaced it. Of course, he had to re-inlet it into a finished rifle. They machined the outside dimension a little larger on the replacement.

[Justin Urbantas]

It's especially confusing because it is a rifle I've had for 17 years and fired thousands of rounds from it. I noticed something off at the bullseye shoot at our rendezvous.  At 25 and 50 yards I was dead on and shot great groups, but at 75 yards I was 8" off to the side.

[Bill Madden]

Justin,
The barrel referenced by Bob that I had a problem with was a Colerain, not a Rice. But that is not material here.

The fact that you have shot the gun for 17 years without a problem and that the windage varies only at distances over 50 yards suggests to me that the problem is not with the barrel or the gun.

Two things come to mind as possible sources of your problem: range conditions and you. Perhaps range conditons vary down  range, so that either light or wind conditions differ at the longer distances. Shooting at different times of the day or at a different range might disclose,or rule out,that  as a problem.

Secondly, perhaps your stature has changed so that you no longer fit the gun like you used to, or, maybe, you have developed a slightly different hold, or God forbid, a slight flinch when shooting at the longer distances. Have a buddy observe you shoot alternately at 50 and 100 yards to see if you are doing anything different when shooting at the longer distance.Otherwise, I am as perplexed as you.

[smylee grouch]

One thing to consider if shooting off sand bags. Are the bags level? If not the recoil can throw your shots to one side.

[D. Taylor Sapergia]

Justin I know you have had great success with that rifle, so I suggest you continue on with what has worked well in the past.  But my load for .45 calibre is 70 gr. FFFg GOEX, .020" denim patch (any lube that saturates the cloth) and a .440" round ball.  I never change the load for different ranges, just the sight picture, But for 25, 50 and 75 yards, my sight picture is the same - dead level.  For 100 yards, I show a piece of the front sight equal to the sight's thickness above the notch of the rear sight plain, and always hold centre.