Sight Adjustment

[eagle24]

I have a rifle shooting 2" high at 25 yards and 7" high at 50 yards with the load I want to use hunting whitetails.  I want it to shoot 2" high at 50.  How much can I safely take off the rear sight before I go back to the range?  It will be a lot easier to do some filing at my shop where I can put the barrel in a vise.

[SCLoyalist]

The rifle's distance between front and rear sight is a necessary piece of info.  You want to make the rifle hit 5 inches lower at 50 yds (or 1800 inches).   You would need to lower the rear sight  by 5 times the Sight radius divided by 1800.   So, if there were 24 inches between front and rear sights (and your rifle's sight radius is no doubt different),  you'd need to lower rear sight 5*24/1800 = .0666 inches (i.e.  approx. 1/16 inch).

Since you asked about 'safely' taking off height before going to the range, I'd say maybe half that in the shop, and fine tune the rest at the range.

[eagle24]

The rifle's distance between front and rear sight is a necessary piece of info.

Sorry, didn't think about that when I asked.  I'm at work, but would guess the sight radius is around 28".  42" barrel and the rear sight is almost where the lower forestock ends.  I'll check it tonight, but by your formula that would be around .08" for my rifle.  I may take it down about .05" if that's the case.  Thanks for the info.

[Ben I. Voss]

A little more info to see how figures were arrived at: 1800 is the number of inches in 50 yards. FWIW

[smylee grouch]

Use a safe file(smooth on sides) to file rear sight down so as not to file any ears off if your sight has them.    Smylee

[SCLoyalist]

As an added thought, you would get the same effect by raising the height of the front sight by the amount shown in the formula.  Depending on the size and style of front sight, and dovetail dimensions, it might be easier to put in a new higher front sight and file it down as required; e.g. if the formula says the sight adjustment needed is .016",  put on a front sight that's .200" taller than what you have now and file it down to bring the impact point back up.   I've found it easier to file a thin blade than a wide rear sight.

[eagle24]

I think after hunting season I will make new front and rear sights.  I've never been really happy with the sights.  Front one is too narrow and I don't like the look of the rear.  Problem I have right now is time to get anything done.  I think the easiest and quickest fix will be to take the rear sight down and hunt till the end of the season.  I also need to tweak the barrel a little for windage.  It's shooting a little left with the sights perfectly centered on the top flat.

[D. Taylor Sapergia]

I wouldn't "tweek" the barrel if I were you, unless all other options are exhausted.  It is unlikely that it's bent, though it could have run out in the bore...closer to one side that the other, at one end.  I'd move the sights in their dovetails to account for the windage problem, and be happy with that, before I would bend the barrel.  Also, check the muzzle for squareness, and the crown for trueness.  Both of these will cause windage issues, if not perfect.

[Herb]

Here's a chart I prepared.  It is on page 2 of Tutorials, "Cutting Sight Slots and Fitting Sights".  SCLoyalist is correct.

[Stormrider51]

In 40 years of gunsmithing bending a barrel was always the absolute last resort.  Muzzleloading rifle barrels are pretty strong and by the time you think you have applied enough pressure to bend it at all you will probably have gone too far.  I had barrels come in where I could look down them and see the "S" curve where the owner bent them one way, went too far, and tried to bend it back.  If the front and rear sights are dovetailed you can move the rear one the way you want the shot to go and the front one the opposite direction.  You should be able to bring your point of aim and point of impact together while keeping the sights centered enough that it dosn't look bad.  And, like Mr. Sapergia said, check the muzzle for squareness and that the crown is even all the way around.  While you're at it be sure you aren't canting the rifle when you shoot it.

Storm

[James Wilson Everett]

For sighting in a gun I leave the front sight high - so the gun shoots low.  Then I file the front sight to bring the bullet impact up to about 2 inches high at 25 yards.  This is the easy part.

For left/right I bend the barrel to bring the bullet impact in line with the sights.  I know that this will cause fits for some!  I make my own barrels and straighten them at least twice before the gun is finished, each time a cold bend by eye.  The first straightening is done just until I can see light through the bore.  This is done with an 8 pound hammer and anvil.  It is surprising how crooked a forged wrought iron barrel is at first.  The second straightening is after honing with an armory reamer and before rifling.  After rifling it is impossible to look through the bore to determine straightness - all you see are the spiral grooves.  (At least I cannot do it)

After the initial sight in I determine which direction the barrel must be bent.  I place the barrel (out of the stock) on the top platen of a table saw mounted on vee blocks about 2 feet apart.  I measure down to the platen surface from the barrel center point.  Then I tighten a big C-clamp to flex the barrel, then release the clamp.  I measure again to see if there is any permanent bend.  Usually the is no difference from the initial measurement.  Next I tighten the clamp a little more and repeat the measurement.  Eventually I get a permanent deformation of 2 to 4 thousanths of an inch.  Of course you cannot see this without a dial caliper.

Next - back out to the range for another trial.  Perhaps this bending may need to be repeated a few times to bring the bullet impact on center.

I am sure that those who use modern precision manufactured steel barrels will not need to do this.

Jim Everett

[dannybb55]

 

[George Sutton]

If you think you need to bend the barrel give it to someone who has experience doing it. Bending barrels is a good way to ruin a nice rifle.

Centershot

[James Wilson Everett]

Centershot,

Your advice is very wise, thanks for the comment.  Guys, please don't try this at home, it may create a bigger problem.  Maybe in the near future I can show a series of photos of barrel straightening so we can get a better idea of how it is done.  I just have made a wrought iron, octagon to round barrel, about 0.41 caliber.  Unless a miracle happens, it will require straightening.  This may a good candidate to do a photo show-n-tell on how to straighten a barrel.  Again, with a modern machine-made, precision barrel, straightening should not be required.  However, with my barrels it is another matter altogether.

Jim Everett

[Don Getz]

Storm......as a former barrel maker, you would find that in the process of making a barrel, many of them will warp and will
require straightening.   No problem, we do it with an arbor press and a good eye...........Don

[Daryl]

It's rare to have to bend a modern barrel, but some do get bent in shipping, and some are not bored straight to start with.

I had one such crookedly bored barrel on a rifle I had traded for, in that the hole was off to the right side at the breech, and off to the left side at the muzzle. Of course, this one needed the front sight barely hanging onto the dovetail as it was pushed way to the left and the rear sight was barely hanging in, moved to the right.  The barrel should never have left the manufacturer, and/or should have been breeched and mounted with the offboring up and down, not left or right.  Bending might have worked, but perhaps not for all ranges due to the amount it was 'out'.

It's rare but can happen.

Les Bauska had a barrel straightening machine in front of one high window in his shop, back in 1975, when I visited him in Kalispel. He showed me how to straighten barrels on his machine and I spend about 2 hours doing just that - straightening a lot of barrels. It was fun - for a while. Most needed only a little tweeking and some none at all, while others had 'bent' while in his bed-planer-type milling machine having the flats gouged on. They were already rifled.  

The conscentric rings are what one looks for and non-round rings show the bending area.  The barrel sat in two anvils (V blocks) angled upward to the window. Another V block above &  centred between the two lower blocks, to push down was controlled by a wheel with pegs looking like belaying pins sticking out radially around the wheel.  You merely pulled a pin towards you which turned the overhead shaft on a fine pitch screw and the the overhead anvil pushed down onto the barrel, bending it. Turning the peg back lifted the anvil and looking through, you could see if the barrel was straightened at that point, or needed more 'work'.  It seemed easy to not go far enough, but the barrels also sometimes seemed to not want to bend at all and needed a LOT of work - many attempts to get the bend to 'take'.  Too - I was new to this, unskilled and was very careful not to destroy any barrels.

Bending finished barrels was a good experience - and not easy, as James noted.

[Stormrider51]

Storm......as a former barrel maker, you would find that in the process of making a barrel, many of them will warp and will
require straightening.   No problem, we do it with an arbor press and a good eye...........Don

What we used to do was use a "bow" to check the straightness of the bore.  A length of fishing line was dropped down the bore and tensioned between the two ends of an arched wooden rod.  The arched rod was allowed to hang below the barrel which caused the taught string to lie along the bottom of the bore.  Hold the barrel up so you can look down the bore with a light source shining down it.  Look for low spots revealed by a shadow underneath the string.  Mark any low spots with a wax pencil on the outside of the barrel.  Rotate the barrel slowly and mark any additional low spots found.  A perfectly straight bore would have the string in contact along the full length.  This is actually harder to explain than do.  I used a hydraulic press and a pair of V-blocks to apply pressure taking into consideration that the barrel will bend and then spring back to some degree.  It's as much an art as a science.

Storm 

[James Wilson Everett]

Guys,

I will be posting a subject on how I straighten forged wrought iron barrels in the tutorial section.  Check it out as we have wandered far from the subject of sight adjustment.

Jim Everett