Removing an SMLE Foresight Block
The foresight block on SMLE Rifles No1 MkIII & III* is a band which goes over the muzzle of the barrel and is located so as to be correctly aligned (upright) by a flat Woodroffe key which sits in a slot milled in the top of the barrel. To keep it from sliding back and forth over the key, it is locked in place with a taper pin which passes through the top of the band and rides in a semi-circular groove cut in the top face of the barrel, which runs from side to side (necessitating a notch in the top face of the locating key for it to pass through).
The taper pin is a small diameter pin, which is always a challenge to get moving, and most importantly has the larger diameter on the left side of the rifle when viewed from the rear. Therefore to remove the pin it has to be driven out from the right side to the left. Replacement is obviously the reverse and goes from left to right.
To remove the foresight block you will require a selection of good screw drivers to remove the timber, a small hammer, a strongly mounted vice with soft jaws, 2 pin punches of the correct diameter for the 'small' end of the taper pin (a short one to get the pin started and a standard length one to tap it through), a pot or box to keep everything together in as you remove it, and in all probability some penetrating oil (WD40 or similar is ideal) and a decent wire brush. Good lighting is essential!
To remove the foresight block, first strip the rifle, removing all timber forward of the wrist of the rifle. It will be advantageous to knock off the nosecap first. The next step is to lock up the barrel of the rifle in the vice. The soft jaws will protect the finish and prevent marking the outside of the barrel. Barrels are fairly robust so although you certainly don't need to hang off of the vice or lock it up with a lump hammer, tighten the vice securely using hand pressure only. The barrel should be positioned so that it lays horizontally in the vice and the edge of the vice jaw is positioned about 1/2" behind the foresight block (chock up the back end of the rifle to take the weight, it will help prevent the rifle pulling itself out of the vice when you start working on it).
Clean off any dirt or corrosion around the foresight block. Clean all around the block, front and rear and both sides so that the pin is clearly visible. If any corrosion is present the wire brush will be the best way of doing this, rifle finishes are surprisingly tough and as long as the wire brush is flexible and not one specifically for scrubbing barbeques, it should not damage the blacking/blueing. Once the cleaning is done, spray the whole area with penetrating oil and leave it for half an hour to soak in. At this stage a couple of light taps on either side of the block with the hammer will assist in breaking any corrosion and help the oil to get in there.
Once the oil has had time to soak in, thoroughly clean the whole area with an absorbent rag to remove all visible oil. Position the barrel in the vice with the right side towards you and in a position where you can see (and access) the end of the taper pin. Using the short pin punch, place it on the head of the pin and give it a firm tap with the hammer. A firm tap, in other words don't pussy foot around with it, but equally do not get the wife to hold the punch in place and swing at it with a lump hammer! The object is to get the thing moving without either missing and 'tabbing' the foresight block into the head of the pin, or spreading the head of the pin with light taps and riveting it into place. Once it has started moving it will become loose quickly and you can just tap it through using the standard drift. Do not lose it! When they fall out they have a nasty habit of disappearing never to be seen again, so either keep a finger on the far side or put a piece of sticky tape very loosely on the left side to gather it up as it comes out.
With the pin out the foresight block can then be tapped forward towards the muzzle until it comes clear. Keep the pressure as low down to the barrel as possible and use light taps only. A brass drift or piece of hardwood should help to prevent damage if it is a tight fit. Make sure that you do not lose the key once the block is off. If it has stayed in the barrel, lift it out and keep it safe. Take the opportunity to clean the outer diameter of the barrel with the wire brush or some steel wool and oil, and the inside surface of the foresight block band, while it is off. It will make refitting it easier.
Once the inner band is slid into place (do not forget it!) replacement is simply the reverse procedure, ensuring that the pin is refitted from left to right (thin end first) and that the key is replaced and correctly positioned before fitting the pin (use the standard pin punch to make sure it is all aligned before tapping the pin home).
The job is a lot simpler than it probably sounds, as you will see once you are into it. The critical thing is the first firm tap to remove the pin. The firmer the barrel is held the more chance there is of getting the pin to move first off, as the force of the blow has nowhere to go except where it is needed. Make a careful note of the warning about losing the pin. It is not unknown for the first blow to be so decisive that the thing launches itself straight out of the left side and can be heard pinging around the workshop until it comes to rest in some dark corner, never to be seen again!