Rifle Sight In 101

 

 

 FIREARMS INFORMATION

 

 

There seems to be a mystical part about sighting in rifles.  Here I will make an effort to try to unravel some of these in simple terms.  Any firearm needs some form of aimament that corallites the bore/bullet with where the bullet will actually hit if it is to be effective.  This method of aimament will be sights in some form or another.  The most simple iron sights on a rifle are a Vee notch rear sight a post type front sight.  In use when properly aligned, by looking over the Vee rear sight and at the front sight, (either a post or a bead) and when the two are in alignment & properly adjusted, the bullet should strike where the sights look for any given distance.  This is called sighted in.

Usually both iron sights will be installed into the barrel in dovetailed grooves thereby holding in the sights while at the same time allowing horizontal adjustment.  Many front sights can be dovetailed into screwed on bases or ramps.  Vertical adjustment is gained by either using a front sight the proper height and/or a long tapered, notched rear sight elevator.

This type of sights have been around since rifles were invented, but has some drawbacks.  For those of us that belong to the "Over the Hill gang" it is hard to focus on 3 object as the same time.  (1) the rear sight, (2) the front sight (3) AND the target.  Plus the fact that if the person who sighted it in used a course bead (saw the whole bead in the rear notch) and the person who may be shooting it at any given time is used to taking a fine bead (seeing less of the round front bead) the point of impact will be lower.

Enter receiver rear sights (sometimes called peeps).  Here the same front sight can be used but the rear sight is moved off the barrel and farther to the rear.  This type of sight will have both windage and elevation (horizontal and vertical) built into the base or the over arm.  Also instead of a Vee notch it has a small round hole that is looked thru called an aperture.   This simplifies aiming as it then only requires seeing 2 objects as your eye naturally centers what ever it sees in this round aperture hole.  It can also be more accurate.

Optical scopes take this to a upper level.  Here you will usually have a magnifying effect.  Normal modern rifle scopes can be had in 4 power, (normally written as 4X), 6X, for fixed power or 1 1/2 X 5, 2X7, 3X9 etc. if a variable.  Many will also be labeled as say 3X9X32.  This last number is the diameter of the front lens in millimeters.  When using a scope, the optics place the alignment on one plane helping those of us with older eyes.

Things That Effect Sighting In ;  Since gravity effects all things on this planet, even if a bullet is traveling downrange at possibly from 1800 up to 3000 FPS (Feet Per Second), it will start falling as soon as it leaves the muzzle.  This is called trajectory.  Therefore you will have to decide at what point that you want your rifle sighted in for.   A 22 RF tin can/ rabbit rifle will normally be sighted in for say 50 yards while a hunting rifle will usually be at 100 or 200 yards.  What this really means is that this is the point where your line of sight crosses the bullet path.

Now let me back up a bit as your sights will be above the barrel and you will need to adjust the sights so that the barrel is pointing slightly upward otherwise the bullet's drop out any distance will be enough that it would be hard to compensate enough to hit anything out there.  So in reality you will have the bullet crossing the line of sight twice, once close to the muzzle and again at where you hopefully have it sighted in for.  This closer crossing is called Point Blank Range.  It can be useful to a deer hunter in that there is the possibility of encountering a grouse at very near this PBR.  Knowing this, it is possible to shoot the grouse's head off with a big game rifle, which may be from 25 ' to 50'.   Iron sighted rifles will have a closer point blank range that a scope sighted rifle because the scope will be about 1 1/2" above the bore while iron sights will only be about 1/2"

So in reality the bullet will be making a arc, with it being flatter closer to the muzzle because the bullet is going faster here than out there, since the farther it goes the slower it is going hence dropping faster as it slows down.  Now mixed into this formula will be rifle ammunition usually comes in different weight bullets.  This to take advantage of possibly needing a lighter bullet to effectively shoot a deer as compared to a larger elk where more penetration is needed.  All cartridges are loaded to safe levels of energy set by SAMMI, therefore lighter bullets will go faster than heavy bullets. 

To take advantage of this, say you had a 30-06  150 gr. bullet and anticipate that your maximum range to be 300 yards.  Using known trajectory charts, you may want to adjust your sights so you are hitting 2" high at 100 yards, which will put you about dead on at 200 yards and then possibly 9" low at 300 yards.  Using this sight in, for a deer sized animal, your "dead on hold" will be out to about 250 yards, but you may have to hold higher like possibly to the top of the back at 300 yards.  Here 250 yards is called Maximum Point Blank Range.  The real secret here is range estimation on your part when you get beyond that 250 yard mark.   And that is where the lazer rangefinders can come in handy.

A rifle sighted for this 150 gr. ammo will not hit the same place of impact as with 180 gr. ammo.  Even changing brands of ammo using the same weight of bullet may make for different impact points.   Each needs to be sighted separately, unless you have an exceptional rifle.

The bullet path above the line of sight is known as Mid Range Rise.  With True Zero at the intersecting point of the bullet path & line of sight.

Trajectory of a hunting rifle
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In any accurate shooting, you need to squeeze the trigger in a manner that you will not be able to anticipate when the shot will go off.  If you jerk the trigger there is a VERY GREAT chance that you will also move the rifle, thereby throwing it off  the target.  You should learn to be able to "Call The Shot".   This is when the shot goes off, you need to have concentrated enough so that you can in your mind "See" the last location the sight was when the shot was fired.  This will also help you later during actual hunting where you can identify where the sight was & where the animal was hit.

How to Sight in a Rifle ;

BE SURE THE GUN IS UNLOADED.

(1)  Adjust your sights as close as possible before you get to the range.  This can be, if a bolt action rifle remove the bolt, look thru the bore at an object some distance away.  Now using the sights look at the same object.  Adjust the sights to coincide with the bore.  An optical bore-scope can be also used on iron sights as described below. 

If your rifle has a scope, do the same or use an optical bore-scope.  You will be able to see your rifle scope's reticule superimposed on the bore-scope grid.  These bore-scopes usually have a grid of lighter lines and heavier lines in the center.  All this equates to 100 yards.  Using a optical bore-scope, everything you see here is backwards, which means what if you see your reticule low and right, it would actually be high and left.   Then depending on the bore-scope brand, most of the individual grids equal 4" at 100 yards.

(2)  Use a rest off a bench or sturdy table, log etc.  Do not shoot offhand to start.  Sandbags work great.  You will need 3 sandbags, 2 in front under your forearm and 1 under the butt-stock.  Sandbags can be made from old jeans pant-legs or get ahold of a friend who trap shoots and see if you can con them out of some used birdshot bags as these are about the right size.  Other than that, there are numerous mechanical adjustable rifle rests that work great.

Note the ear plugs


Also beneficial would be a pair of good binoculars or spotting scope to be able to see your bullet holes with otherwise if you are on a public or even private range, if other shooters are present, you will have to wait until they call a halt so all can go forward & change targets in safety.

(3) WEAR HEARING PROTECTION.

(4) It is best to not start shooting at the 100 yard target.  But one at 50 yards first.  The reason is if you miss the 100 yard target, (unless you have a large backing paper behind it) you may fire a lot of ammo and still not know where the rifle is hitting, but if you start closer, your chances are better to at least hit the paper thereby giving you an indication where you will need to move the sights to.

(5)  Once you have a hit, fire a couple more to verify that the rifle is indeed shooting close to where the first round hit.  Shoot for a group.  A group fired from a iron or open sighted rifle will be considerably greater than one from a scope sighted gun simply because with the scoped gun the shooter can see better.   A 2" group is good for a scope sighted hunting rifle, varmint hunters will not settle for anything less than 1".  And match shooters are unhappy if all the holes are not touching.

Here now you can use your bore-scope.  If you see your rifle reticule to the right by a grid and high by 2 grids, you need to adjust the rifle scope to be in line with the bore-scope.  Now since using the illustration above for the 30-06, where you want your rifle 2" high at 100 yards, you will want your rifle scope to be on the heavy vertical in the center of the grid and 1/2 a grid LOW below the horizontal heavy center line. 

Or adjust the sights so to match your intended point of aim.  For iron sights, this means tapping the sights right or left.  If you need to move the point of impact to the right, move the rear sight to the left.  And if you need to shoot higher, move the rear sight elevator higher.

Method A ;  Scopes will have a turret cover that when removed will allow you to adjust the internal adjustment in the scope.  Most scopes will have turret knobs in the center of the scope, covered by threaded caps.  The top turret is for up/down and the right side turret is for right/left movement.  They will usually have marks on this turret adjustment ring.  Some will also have click adjustments.  Most will have marked somewhere under the cover just how much each mark or click equals.  Most hunting type scopes will equal 1/2"click at 100 yards.  Target scopes may have 1/4" adjustments.  Some hunting type scopes do not have clicks, but friction adjustment.  These will have marks on the knobs referencing the 1/2" adjustment.

So if you have a hunting scope, you need to move your point of impact 2" in this case that would be 4 clicks or marks.  By looking at your point of impact on the target and making this adjustment, then shooting again to verify that you are right, you can sight your rifle in.  One suggestion is that before you make a adjustment on the scope turret adjustment ring that you either make a slight mark at where zero is so that if you went the wrong way, that you have a reference point to return to.  Some of these rings are held on by slight friction or small screw & can be re-zeroed instead of marking or remembering.

Fire 3 or 4 rounds to confirm your new setting.   Do not shoot so rapidly that the barrel warms up as this will effect the point of impact as it gets hotter.  When you are finished remember to pick up your scope turret covers, as many are lost in this manner.  And most scope manufacturers do not use a universal diameter or thread.

Method B ;  Another method is after you have identified where bullets are hitting, is to place the rifle back in the rest, line it up exactly where you were holding when you shot, (like on the bullseye).  With the turret covers off if a scope sighted rifle, using a screwdriver and without allowing the rifle to move, adjust the scope knob to where the previous bullet hit the target or in relationship to where you want it to hit from where you aimed.  It is easier to do this for the vertical adjustment than the horizontal as you need to put some side pressure on that turret knob.  But this is a faster, more reliable method and usually can be done with lesser shots fired.

Once you are satisfied with how your rifle is sighted in off the bench, you might consider trying a few offhand shots.  Simply because you can get in a situation where there is nothing for you to rest on out in the field.  It is a whole lot different than shooting off a solid bench.  However my suggestion would be to do more practicing offhand with a 22 RF simply because of the ammo expense.

Things That Can Effect Accuracy :

If you can not hold a group of at least 3" at 100 yards with a scope sighted rifle, something is wrong.  Most modern hunting rifles are capable of at LEAST doing 1 1/2" 100 yard groups, if the shooter does their part.  If worse than that it could be you flinching, or the following.

Scope Mounts Loose ? 
If you are chasing your tail in trying to sight in your rifle, are the scope mounts loose?  This would be the number one thing to look at.  It could be either the scope base screws into the receiver being loose or the ring clamp screw.

Scope Loose Internally?  If you happened to take a hard fall, the scope could be broken internally.  The simple quick check here is to remove the scope from the rifle and shake it.  If you hear a rattle, send it back to the manufacturer. 

It could also be the scope is sticking internally and not responding to your adjustments like it should.  When this happens, you have adjusted it to where you think it needs to be after firing some shots.  OK, but now the shots are in a different location than you thought they should now be.  You readjust and the same thing happens.  Time to send it in for repairs if the company is still in  business.

Scope Focus ;  All scopes also have a focus adjustment.  Not everyone has the same eyesight.  You may see thru the scope and it could be clear at close range, but fuzzy farther out.  You need to turn the adjustment ring so that it is in focus for YOU at all ranges.  This means if you pick up a friends rifle, you may not be able to effectively shoot it accurately.  Also even if you have not used your old standby rifle for a number of years and you have not taken into account that your eyesight may have changed.  You may be able to see the country side but the crosshairs are fuzzy enough that you can not define your point of aim (I have witnessed this happen).  Did you get your glasses changed or had cataract surgery?  Either of these could effect your vision enough that you should at least check or if need be to refocus your scope. 

Rusty Bore ;  It goes without saying that the bore which is the heart of any rifle's accuracy and needs to be meticulously clean and free of corrosion or copper fouling.  Copper fouling can be because of a rough bore & then firing ammo which was imbedded into the rust pockets.

Dented or Bad Muzzle Crown ;  The exit of the bore at the muzzle is important in that if is not true, when the bullet exits, there can be more gasses being pushed on one side than the other thereby setting up a wobble in the bullet.  If you suspect this, take it to a good gunsmith.

Some Ammo Just Not Compatible With Your Gun ;  Yes, not all ammo may shoot accurately in all guns.   Some rifles may have been fitted with a barrel that was intended for lighter varmint type bullets, these barrels can not stabilize heavier bullets.  One caliber in particular would be the 244 Remington.  The factory recognized this, changed the barrel twist, then renamed it the 6mm Remington.  Others may be rather finicky and like only one weight of bullet or brand of ammo to shoot accurately.

Excessively Heavy Trigger Pull ;  If the trigger pull is excessive, it will be hard to precisely pull the trigger.  Usually a good crisp hunting trigger will be set at about 4 1/2#.   A gas operated semi-automatic trigger may be slightly more for safety's sake because of the sharp jarring when the action is operating.   A varmint rifle could be near 3#.
 

You Are Flinching ;  If you have been shooting a high powered, heavy recoil gun for a while, you may be flinching.  This being you are anticipating the heavy recoil & are either jerking the trigger or closing your eyes as you pull or BOTH.  This can be beneficial to the game you are after as you probably will not hit anywhere near where you are looking.

I know one hunter who hunted with a group of friends who all carried 300 Weatherbys.  The story told on him was that they spotted a elk across the canyon, (a long ways, but within range).  He laid the rifle across the hood of a pickup, the others were watching thru binoculars.  One of his buddies was watching him & he closed his eyes and jerked the trigger.  Missed by a mile.   Their hunting expedition was really an excuse to get out with the boys.  OK, what ever tweeks your tweeker.

I know another hunter who had to use a 340 Weatherby, but he would never sight it in himself.  Always some excuse.   Both of these guys could have had some form of recoil reduction done to their rifles IF they would have recognized the problem and confided in a good gunsmith.

Stock Bedding Loose ;  If the metal parts of a rifle are loose which then trends to wobble around in the stock, even slightly, this can also effect accuracy.  Check the action/trigger guard screws for tightness.

Stock Does Not Fit You ;  If the stock is to short and or the scope is mounted to far too the rear, you may crawl the stock, you can be subject to being scope bit.   That is if you are too close to the scope, and under recoil the gun will come rearward.  As the result of this, many shooters have become well acquainted with their scope by it hitting them in the eyebrow.  This can be a nasty circular cut.  And it WILL bleed.

And a Combo of Many of the Above Can Drive You to Drink;  It would not be impossible for you to have a rusty bad bore, loose scope mounts, incompatible ammo and a sticky scope adjustments.  Been There - Done That.  This usually takes some time at the range and lots of ammo for you to sort out.

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Originated 11-26-2010, Last updated 12-23-2013   ***
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