The Rough Guide to Zeroing

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nagarifle
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The Rough Guide to Zeroing

Post by nagarifle » Fri Mar 21, 2008 12:21 am

This guide is not a comprehensive one nor is it intended to be. As much information can be obtained by surfing the net and as all sportsmen have different views and methods. I have made a few observations from experience of others and my own. Thus I can not take any credit for this guide but can take all discredit for it.

First and foremost this is only a rough guide and the writer would advice each sportsman/ woman to have a guide/coach to help you to zero in your firearms.

This guide, mainly deals with rifles however the same principles apply to all types of firearms which need to be zeroed.

SAFETY

Also always keep in mind SAFETY and DANGER when handling firearms.
  • When firearms are not in use i.e. when not on range the firearms must be kept unloaded; that is no bullet in the chamber and the magazine.
  • The bolt/slide should be to the rear or removed.
  • At no time should the barrel be pointed at any one.
  • Never take it for granted that you have applied safety catch or that simply the use of a safety catch makes the weapon safe.
Grouping

The perfect combination between rifle, ammunition and shooter, would be the ability to put every shot through the same hole at any range all the time.

But few things are perfect in this world, least of all arms & ammunition (sometimes the sportsperson).

It is important to understand the difference between consistency and accuracy and the factors that affect them.

Consistency is a measure of how close together a series of shots will fall to each other (group size).

Accuracy is how close a shot is likely to fall to the intended point on a target. This depends on a number of combination i.e. Group size, correct zeroing and the shooter's ability to select the correct point of aim to compensate for external variables such as range (distance) and wind.

Group Size

If we say that all the external influences are minimal and the equipment and ammunition is of good quality, shots should consistently grouped within 1 minute of angle.

1 minute of angle measures approximately ½ inch at 50M and 1inch at 100 M and 2inch at 200 M. (more on this can be had on the net)

However the effect of many external variables increases with range and other factors, all this must be taken in to account.

External factors leading to inconsistency,
  • Taking a slightly different aim for each shot- an imprecise aim will increase the size of the group.
  • Variations in wind or other atmospheric effects between shots will increase of the size of the group.
  • Poor shooting technique will send each bullet off on a slightly different course to its predecessor.
Mechanical factors leading to inconsistency
  1. Ammunition Ammunition can vary considerably in quality performance and consistency. Old or indifferent quality ammunition, mixed batches or mixed bullet weights or loads unsuited to their rifle will all lead to poor results.
  2. Oil and Wet Oily or wet ammunition will give poor results and it will not shoot to where the rifle is normally zeroed. Equally oil or water in the bore can both very breech pressures considerably, which will lead to erratic shots. The barrel should be thoroughly dried out before use.
  3. Powder Temperature Powder can deteriorate over time and burns faster at high temperatures or when under pressure in a reduced space. Ammunition should be regularly turned over and never be allowed to become hot e.g. by being left in the sun. Dented or damaged ammunition must not be used under any circumstances.
  4. Poor Obturation Powder gases must be completely sealed behind the bullet by proper expansion of the neck of the cartridge cases to fit the chamber tightly. Burn marks will be seen on the case shoulders if this does not occur.
  5. Headspace In rimless cartridges this is a distance from the closed bolt face to a datum point n the shoulder of the case. In rimmed cases it is measured to the front of the rim and in belted cases to the front of the belt. Incorrect headspace can cause excessive recoil and exert excessive pressure on the bolt lugs. Sings of incorrect headspace are normally black streaks running down the length of the case after firing.
  6. Barrel quality Heavy, stiff barrels will usually be more accurate than lighter ones but the latter will still give good results as ling as kept in good condition. Poor maintenance or can soon lead to a drop in consistency.
  7. Barrel bedding The rifle action should be rigidly fixed to the stock with mounting screws which must be kept tight. Most rifle barrels are "free floating" forward of the front mounting screw. If the action is not firmly bedded into the stock or anything e.g. the stock/after the fire’s fingers or anything actually touches the barrel itself, the barrel vibrations on firing will be erratic and lead to inconsistency. (To check if the barrel is free floating do the following- take a hundred rupee note or any other note and slide it under the barrel and the front stock/grip. The note should freely slide right up to the front mounting screws.)
  8. Irregular Muzzle and Bullet Base As the bullet leaves the muzzle the hot gases overtake it for a short period. If either the muzzle or the base of the bullet is irregular, the bullet may become slightly unstable until its spin corrects this. Use good quality bullets and do not damage the muzzle by poor cleaning technique for firing with grit in the end if the bore. As the last few inches are very important in relation with the round leaving the barrel.
Zeroing

This is a process by which the shooter adjusts his/her sights so that the centre of his/her group or Mean Point of Impact (MPI) coincides with a selected point on his target at a given range.

If the bullet is not to strike below the Point Of Aim (POA) situate some distance away, the rifle barre must be elevated to project the bullet slightly above the horizontal. This is achieved by adjusting the sights.

How to Zero

Preparations
Zeroing is something that should only have to be done occasionally but it must always be done carefully. Between zeroing sessions, regular sighting shots should be taken to ensure that the sights still remain "on zero".

Do not try do zero in bad light, on a windy or very hot or very cold day.
To zero successfully ensure the following are available:
  • Safe place with plenty of time and no distractions.
  • A clean rifle with sights firmly attached and all bedding and mounting
  • screws tightened.
  • Plenty of ammunition
  • Enough targets with a clear aiming point and or plenty of patches
  • A comfortable lying position (prone)
  • A firm, soft rest for fore end of the rifle and back of the supporting hand
  • A small screw driver
  • Notebook and pencil, Ruler
  • Ear protection
Zeroing a 3 Shot
  1. When sure all shots will hit the target, fire a group of 3 careful shots at the aiming mark at the selected zero range. (In the army five shots are used for zeroing).
  2. The shooter's body should be well aligned with the target i.e. no strain should be needed to keep the sights on the aiming mark.
  3. Make full use of a good rest. Take exactly the same aim each time and try to make the minimum of body movement between each shot.
  4. If a bad shot is fired disregard it. And fire another one.
  5. Three good shots should fall close together forming a tight group at this stage it does not matter where on the target the shots fall but it is important that they should be close together.
  6. If the rifle and ammunition is of good quality, and firer competent, all shooters should be able to achieve a 3-6 cm or 1-2 inch group at 100 M with a good rest and in ideal conditions.
Mean Point of Impact (MPI)

The MPI of a three shot group may be established by joining each shot hole with a line and then drawing a line from each shot hole to the centre point of the opposite side of the triangle. All three lines should intersect at the same point within the triangle. This then in theory becomes the middle of the group or MPI.

For example if the three shots have all gone high and slightly to the left, the sight needs adjusting to right and down. After this a further 3 shot group should be fired to confirm that the rifle is zeroed in to the centre of the target.

It is always best to shoot from different range to see where the shot will fall on the target.

If zeroed at 100 M then shoot from 150 and 200 M. when at this range you will know where the shot falls and can adjust to hit the bulls eye.

Problems with Zeroing

If a tight group cannot be archived or the rifle cannot be zeroed in, then the fault can lie with equipment. However in most cases the fault will be found with the shooter.

To solve this problem a shooter should check the following (this list is not a complete one but a brief one).

With the shooter
  1. Take exactly the same and a precise aim for each shot.
  2. Wear glasses if needed.
  3. Follow through properly – try to see the shot hit the target.
  4. Avoid flinching or anticipating the recoil.
  5. Control your breathing try to be consistent.
  6. Squeeze the trigger rather then pulling the trigger.
  7. Fire from a comfortable position. (Prone)
  8. Making a proper use of shooting aids.
  9. Should avoid drinking alcohol before and during use of firearms and avoid heavy meal.
  10. The whole body should be relaxed and rested.
(Remember: eye + rear sight + foresight + target = bull’s eye)

With firearm
  1. Loose sight mounts or screws.
  2. Warped woodwork pressing against the barrel.
  3. Loose action bedding screws.
  4. Oily or wet ammunition.
  5. Very dirty barrel or one fouled with bullet residue.
  6. Poor quality ammunition or reloads (reloads are not done in India).
  7. Unsuitable bullet weight for the firearm.
  8. Barrel rifling.
  9. Trigger pull may be uneven or too heavy.
  10. Defective iron sights/scopes.
  11. Defective firearm
If a sportsperson is aware of the above and puts it to practice then a good grouping and zeroing should be achieved.

ENJOY A GOOD GROUPING

Bore sighting http://indiansforguns.com/viewtopic.php?f=22&t=10998
Last edited by nagarifle on Fri Oct 08, 2010 6:19 pm, edited 1 time in total.
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Post by bullshitwalks » Fri Aug 01, 2008 12:47 am

thanx

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Re: The Rough Guide to Zeroing

Post by TenX » Fri Aug 01, 2008 10:23 am

Good info... Thanks Bro
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Re: The Rough Guide to Zeroing

Post by browning » Fri Aug 01, 2008 1:02 pm

Good information. Thanks.

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Re: The Rough Guide to Zeroing

Post by mundaire » Wed Feb 25, 2009 3:56 pm

KB article restored, please see the first post in this thread.
Cheers!
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Re: The Rough Guide to Zeroing

Post by eternalme » Thu Feb 26, 2009 12:54 am

Very elaborate one !!

If I had to write the same , I would take a week to write it :-). Concise and to the point.

Appreciable

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Re: The Rough Guide to Zeroing

Post by Kumarnishith » Sat Dec 05, 2009 11:06 am

Great and very informative writeup!! Thanks!!

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Re: The Rough Guide to Zeroing

Post by timmy » Sat Dec 05, 2009 11:49 am

Lots of good advice here!

Sometimes, I put a new scope on a rifle or have to swap them around for one reason or another. When this happens, I set up the Wife's ironing board in the living room and put a thick pillow on it. I rest the rifle on the pillow in such a way that it will stay put.

Opening the window shade, I'll pick out a knot on a board on the back yard fence. This will be about 60 feet from where the ironing board is. The distance isn't too critical. What's needed is the ability to see the knot or other mark on the fence fairly clearly.

I take out the bolt or open the action. For instance, in the case of an AK or SKS, I take off the action sleeve and remove the bolt. The idea is that, from the rear of the rifle, you need to be able to see through the bore.

I then look through the barrel and move the rifle around until I can see the knot centered in the barrel when I look down it. Then, I adjust the cross hairs on the scope to center on the knot as well. This will usually move the rifle also, so I may have to go back and recenter the rifle, then readjust the scope once or twice.

At this point, the rifle is usually good for taking to the range and firing a shot or two at somewhere between 25 and 50 yards. The eyeball adjustment isn't exact, but using a paper plate with a dot marked on it is sufficient for getting things set for the real sighting in at 100 yards.

For hunting, I've always considered that the normal target zone is about 6" in diameter. So, for my .270, for instance, I will sight in 3" high at 100 yards, which makes for a dead on hold well beyond 200 yards with this caliber. By consulting ballistics tables in a reloading manual (the Sierra Manual has some really good tables), I can easily figure out what my dead on hold is when sighted in 3" high at 100 yards for pretty much any caliber/cartridge.

I don't own any of those fancy laser bore sighters, and this procedure has always worked for me.
Regards,
tim

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Re: The Rough Guide to Zeroing

Post by tingriman » Sat Dec 05, 2009 12:06 pm

Thanks for a great piece of information

regards,
tingriman

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Re: The Rough Guide to Zeroing

Post by MoA » Mon Mar 08, 2010 1:38 am

For some reason have only just seen this.

An ideal rifle is both Accurate and Precise. Accuracy is the ability to hit where you're aiming, and precision is the ability to put bullets as far as possible through the same hole consistently.

While I agree with most information, the one bit I do not agree with is that reloads will lead to a degradation of accuracy and precision. Generally if done correctly it is the opposite.

Timmy not sure how you're looking through the barrel from the breech. The design makes it a little difficult to do so. I cant do it with my Vz's at least.

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Re: The Rough Guide to Zeroing

Post by nagarifle » Mon Mar 08, 2010 2:02 am

MoA wrote:For some reason have only just seen this.

An ideal rifle is both Accurate and Precise. Accuracy is the ability to hit where you're aiming, and precision is the ability to put bullets as far as possible through the same hole consistently.
:agree:
While I agree with most information, the one bit I do not agree with is that reloads will lead to a degradation of accuracy and precision. Generally if done correctly it is the opposite.
:agree:
Timmy not sure how you're looking through the barrel from the breech. The design makes it a little difficult to do so. I cant do it with my Vz's at least.
i agree that the design in most rifle would make it difficult, this method is used in the army a lot, and for rifles like the SLR, M16, as when is open and the bolt etc is remove, the stock is somewhat like the shotgun, ie it breaks open and leaves a clear view down the barrel on to the target. and is done for simple reason to get the zeroing done without firing. However for something like the remi 700 etc, where the stock is fixed then it is very hard to see through to the target even with the bolt removed.

in this age as Timmy pointed out a bore sighter, laser or other type more or less do the same thing. As the aim is to bore sighted. (iron sights or scope used)
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Re: The Rough Guide to Zeroing

Post by 1905mauser » Thu May 06, 2010 6:25 pm

nagarifle wrote:
in this age as Timmy pointed out a bore sighter, laser or other type more or less do the same thing. As the aim is to bore sighted. (iron sights or scope used)
Interesting post nagarifle. thanks for sharing.

See left target below. 100m range Iron Sight on my Swedish mauser (Soderin sight). Was trying to zero rifle. Was happy to see the shot at cross hairs. Dont ask me how!!

Image

Image

Another thought just crossed my mind, that to try using the bore scope for zeroing the mauser. Will check and see what happens.

cheers.
Good Miltary and Civilian competitions this weekend. Lets see how it goes.
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Re: The Rough Guide to Zeroing

Post by hornet » Fri Apr 29, 2011 2:30 pm

dear brother;ihave some problem in zeroing my new diana airking as it has atendency to shoot a bit low all methods of windage tried but iam not satisfied only onething is left that the foresight has been pushed ahead inthe slot by my friend from whom igot the gun;should i bring it back.otherwise iam n o hooter with .315 bore ora.22 firearms. but as now i have moved to atownship things are different these air guns are they prone to bad shots or may be i start using heavier pellets....pl your advice...thanks

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Re: The Rough Guide to Zeroing

Post by nagarifle » Fri Apr 29, 2011 2:58 pm

if its shooting to the left move the rear sight to the right, or the other way round.

if shooting high then try to bring down the front sight, the pellet wight might make a difference but it should not effect that much.

try to move the front sight and see what happens,

all the best
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