Why do sights end up not well centered?

[Muleskinner]

This is something I have noticed on a few muzzleloaders and on a rifle I have at this time.......these are fixed sights....is this always a bad thing?...the amount is only slightly off center that you have to look hard for to even see......but the front sight is off a bit....I sighted them in from a sandbag rest at 50 yards and got great groups.....the rear sight is held on with screws and cant be adjusted and it looks well centered............your input appreciated

[northmn]

Three things can put sights off center.
1. Barrel runout whcih means the bore is not quite centerd to the outside
2. Bent barrel
3  Crown slightly off.

Another possibility is that the front sight may have a lean to it.  If it works don't fix it.

DP

[Daryl]

Most barrel makers today, chuck barrels on centres to grind/scrape or mill the flats.  Theoretically, this should put the hole in the middle, however, the hole can be in the middle at each end and not in the middle, in the middle.  The sloping angle to the middle at the muzzle will cause the impact to be to one side, high or low.  With a barel such as this, there is more steel on one side than the other, and the barrel will be prone to walking it's shots as it warms up, and again as it cools down.  Kept at the same temp, the groups should maintain the same point of impact.

More barrels are slightly bent, than some people realize.  Barrel harmonics on firing are not just up and down, but in a circular as well.  The point of delivery or the ocilations effects the final point of impact.  With all these 'causes' of innaccuracy occuring, it is amazing we can actually hit anything with our guns.  The effects are minute, of course, but can compound to create problems - in some barrels.

[Artificer]

Northmn,

Muzzleloaders and suppository arms are alike in this context.  When you zero M1911/A1 pistol sights, or M1 or M14 sights, the front sight is usually off center a bit (and when the pistol has a moveable front sight that is).

On many modern firearms, the front sight is centered, but we often don't think about the adjustable rear sight being off one side or the other.

Also, a lot has to do with how far we shoot the rifles.  With muzzleloaders, we don't normally shoot at quite as far of a distance.   

Team Shooters with the M1 or M14 set their rear sight to zero windage and then move the front sight to center the group on the target.  That way, you have the largest number of clicks of windage available as you go back to the 300, 600 and even 1,000 yards and as a result of how the wind is blowing while you shoot.

Finally, beside the bore of the rifle being off inside the barrel, we also have to deal with each shooter's individual shooter's eyesight.  Everyone has different vision capabilities and we often have differences from the rear sight to the eye and where we place our cheek when shooting.

Gus

[northmn]

I suppose the spin from rifling could also add to a side wise drift, which would be consistant.  I noticed a diffeence between boat tailed bullets and flat based when I changed loads once.  The boat tailed shot quite a bit to the right.  Round ball might be affected somewhat the same.  Just started working on my 58 for deer hunting and had it pretty close through measurement of cnetering and height.  May not be totally centered but it is very close.

DP

[Daryl]

Modern guns develope much more pronounced whip ocillations which have a direct result in bullet impact. Less so in the ML, but it's still there.
As far as rifling drift, it's there, but not noticable for accurate modern guns until about 300 to 400 yards & about 10" to 14" at 1,000 yards IIRC. That's for 10" twists.

In our ML rifles, the twist direction drift would not be noticable at any range, me thinks.
 
There can be a drift for sure though, due to sights being way off centre for zero to correct a major defect, ie: bent barrel or warped barrel. In my opinion, the ball will continue to drift to one side, more and more as the range increases, just as with a double rifle that causes the balls to cross or diverge, the balls will continue in that direction.  For example if zero'd (both barrels hitting the same hole at 50 yards, the balls, due to being directed towards each other to match the sights at 50, will cross past 50 yards and continue to shoot wider apart as the range increases.  If they diverge(shoot apart), they continue to diverge.  Only if regulated to shoot parallel with the axis of the bore, will they continue to shoot in a straight line at all ranges.  This same thing happens with a bent barrel - The barrel is bent to bring the point of impact to a centreline of the barrel's outside, but past that sight-in range, the ball continues to cross (fly away from the line of sight). How much hopefully - within usable range - but it is happening.  With a rifle, it could be noticable- perhaps?

 

[T*O*F]

the amount is only slightly off center that you have to look hard for to even see......but the front sight is off a bit

The math wizards will give you all kinds of esoteric answers except for the simplest one.  The flats are not always equally machined and while the sight is actually centered, it gives the illusion of not being so.

[Daryl]

Yup - didn't think of that one, but that's possible too, of course.  Especially if it's a Bauska barrel from the 70's where no 2 flats were the same size, even - but - the barrels were accurate and gave an early lession in draw-filing.

[Pete G.]

Everybody always wants to blame the precision machined barrel and not the hand filed notch in the cast rear sight. Why is that?

[Muleskinner]

Everybody always wants to blame the precision machined barrel and not the hand filed notch in the cast rear sight. Why is that?

This a good thought...I have been looking at that myself....since the sight is fixed type....and the notch already there.....it looks to be centered but hard to tell really...since its sighted in at 50 yds I am gonna try it at 100 yds and see if the left and right point of impact stays the same

[Daryl]

Everybody always wants to blame the precision machined barrel and not the hand filed notch in the cast rear sight. Why is that?

Aren't your dovetails and notches precision machined, filed or cast, Pete?

 The barrel might have been 'precision' machined, absolutely perfect as it came off the mill, but was not quite precision handled as it was then dropped in the shop, or had heavy boxes piled on it during shipping, or dropped and stepped on by the guy driving the big brown truck before you got it.

Gads, could THAT really happen - you bet it could and does.