Tang mounted vernier sights

[PlaidSon]

I've been looking at some tang mounted sights and was wondering how to "zero" a set of aftermarket sights for a particular distance (100 yards).

As far as I can tell, you adjust the front sight to compensate, learn where on the vernier shoots bullseye, or shim the rear sight.

I hope that makes some sort of sense.

 

[fingers284]

Any vernier tang sight worth buying will have an elevation adjusting function built into it. All the better quality ones (soules sights for example) also have a horizontal adjustment screw as well. If they don't, the horizontal zeroing is accomplished by sliding front sight in the dovetail slot.

There are two things where shimming is required. First is if the tang sight sits on the gun canted (not perfectly centered & upright) to one side or the other. shimming can be used to correct a miss-alignment . The second is if you have no dovetail at the front sight for right/left adjustment and no horizontal screw on the vernier, then shimming can be used to purposely cant the vernier to one side or the other for slight horizontal impact changes .

 

[PlaidSon]

So theres enough elevation adjustment to compensate for different tang angles and those sort of things to get the zero at your preferred distance?

 

[BCRider]

The mounts come with an adjustable leaf spring detent that fits into a notch on the lower knuckle of the staff (the vertical part). You slide that detent spring back and forth so when engaged in the notch in the staff's knuckle that the staff sits vertical to the muzzle bore. Or to the outside of the barrel for constant section barrels.

On the "Soule" style rear sights the staff is tall enough that you've got ample elevation range for just about any use you can think of. There's more than 3 inches of adjustment on any I've seen after all.

You don't really "zero" the rear staff. Instead you adjust the peep traveler on the staff until your POA matches where your gun is shooting at the distance in question. Then, using your best reading glasses to see the teeny tiny numbers and vernier hash marks, you take note of where the peep is sitting and write it down. That's your zero for that load at that distance. Repeat for other distances and write THOSE values down too. And take note of the air temperature and overall weather since that affects things as well. Keep that notebook with the rifle and sights for this reason since we all have fallible memories. And the numbers on the staff are not range readings. They are simply numbers. On the two Pedersoli Soule rear sights I've got the markings are a simple metric centimeter ruler with a vernier to gauge the values down to 1/5's of a millimeter.

The little knob on the top of the staff is connected to a long screw that is used to move the traveler with the peep up and down the staff.

I would say that most of the rear staff assemblies come with a windage adjustment. But that it's best if you can to set the zero windage at the dovetail of the front sight. But if you can't do that then set and make a note in your notebook about how much windage on the rear adjustment is needed for zero wind days.

For any of the slimpler and less expensive rear sights without windage you're sort of stuck. In that case ALL of the windage adjustment needs to be done at the front sight. And you will want to take special care to get the rear tang sight mounted "just right".

Then there's the shorter Marbles style rear tang sights. That's the ones where there's just a single post instead of the ladder style open frame. For those the vertical adjustment range is limited. But the lower barrel screw section can be fitted with different upper staffs with different lengths to suit various guns. If this is the sort you want then you will need to study the listings from Marbles or Lyman to find the one that your rifle needs.

The rear staff also depends on which front sight you're using since that alters the height of the sight line too. Switching from a simple front post or bead to a globe style will raise the sight line and may require a taller rear staff in a Marbles style tang sight.

Even how you mount the sight matters. For best sighting the peep has to be pretty close to the eye of the shooter. The bases are typically not symmetrical. So depending on which way you mount the base the ears that hold the staff may be sitting higher or lower on the slope of the tang. And depending on where you find you want the position of the rear peep to be this can affect which height of staff you need on a Marbles style tang sight setup.

With so many options to play with all you can do is try to select the one you best think will work for you and be prepared to buy a different height staff in case you guess wrong or find that you want to switch around the base to move the peep a little back or forward.

 

[PlaidSon]

Damn. That really clearified things. Thanks for the lengthy detailed write up. As a machinist I am familiar with reading many vernier scales so i do understand the readings are just numbers. I think in alot of cases fractions of an inch.

Thanks again, I can't wait to stare through one of those little beauties.

 

[BCRider]

No problem. I sort of got the idea that this was all new to you from the nature of how you posted the question. Hope the time I took helped others as well.