If you have just bought a new rifle and you are lucky enough to be able to visit the National Shooting Centre at Bisley then your next port of call should be the Range Office, where you should ask for a Zero target for a 303 and they will give you a card that looks like this:

It costs a fiver for which you get 20 mins on the range, and the actual card is much taller than my diagram.

This card will only work on the zero range because the zero range is only 71 feet 7 inches long and the card is scaled to match that distance.

There is a range register in the range office in which you have to enter your details before using the zero range.

It can be quite busy when there are competitions on.

Note; These instructions are intended only for use with a .303 Lee Enfield service rifle, but a 7.62 card is available though and works in a similar fashion. Similarly, it is only intended for use with standard ammunition, hand loaded ammunition may give inaccurate results.

The way it works is really easy.

You should first boresight your rifle by removing the bolt and checking that when you look down the bore you can see the target, and then, without moving the rifle, check that the target is also visible through the sights.

Also check that all the screws on the rifle are tight and nothing is wobbling around and about to fall off.

Then load the rifle and adopt the prone supported position.

If you have sights that include windage adjustment, make sure that this is centred or set to "0".

Set your rearsight to the range of your choice.

The black semi-circle at the bottom of the target card is your aiming point, you place the tip of your foresight blade at the base of the semi-circle (in the same way that you would with a traditional "Tin Hat" target).

When you fire a shot the sight setting and the POI should correspond to the setting in yards on the left hand scale on the card.

It is NOT a good idea to start with your rearsight set at 200 if this is the first time you have done this with a new rifle, the end result if you do this is often an entirely obliterated aiming point which makes the rest of the exercise somewhat harder.

400 or even 500 is better, I know we seldom shoot at those ranges, but setting your foresight for that and using those points means that we can make a horrible mess on the card higher up, away from the marks that really matter to us most of the time (200 and 300).

Adjust (or change) your foresight blade until your MPI on the card matches the range set on the rearsight, (see the previous page and the next page for all the technical stuff) then wind your rearsight down to see if it is also accurate on 300 and 200.  Once it is, then it is time to take the rifle to the 100 metre firing point and fine tune it (see the previous page).

If it fails, then take it to a qualified armourer.

Use rests, bags or whatever it takes to keep the rifle as steady as possible.

Take no notice whatsoever of the scale marked "Inches" on the right of the card at this point, there may be a further page on that at a later date.

You may notice that the 303 card is marked "SR(b) Minutes" at the top, whereas the 7.62 card is marked "True Minutes". The reason for this is the difference in length of the sight base between SR(a), SR(b) and 7.62 target rifles and is linked to the fact that the zero range is 71 feet 7 inches long.  I could (and might) write a whole article on that subject, but just trust me, it's not going to help you at this point.
Many thanks to Nick Grimm, Paul Quilliam, Mick Kelly and John Bloomfield for helping me out with this.