In recent issues, we have looked at gunfit and shooting vision generally, and we have looked at the specifics of length, pitch and drop. The time has come to consider cast, which, in many ways, is the most complex of all the gunfitting variables and almost certainly the most misunderstood.
Put simply, cast is the extent to which the stock is angled; angled to the right it is known as cast-off and to the left, known as cast-on. Most clay guns have some cast-off built into them. It can be an especially important variable for those who have less than absolute eye dominance in the eye looking down the rib and notably for those of large frame and/or who have broad shoulders and a well developed chest.
Cast is normally measured at the heel and toe of the butt. Some top gunmakers, however, will measure cast ‘at face’ as well. This is the cast at the mid-point of the comb where facial contact would usually be made. Bespoke makers may also build in cast to the action itself and in particular the top and bottom straps of the action. On cross-over and semi-cross-over stocked guns – which have become something of a rarity and have an evident dog leg built into to them – you may see the cast built into the lock plates as well. In other words, the plates or locks may have a distinct curve to them, which can cause a problem if you want to restock a cross-over gun to straighter dimensions.
On an average over-and-under standard dimensions for cast would be about 1/8” at heel and ¼” at toe – though Brownings tend to have very slight cast at heel and the toe is angled out a bit to the right. Differences in cast to heel and toe as commonly seen may be explained by human anatomy. The mass of the pectoral muscle and the fatty tissue over it, may call for the sole of the stock to be slightly angled to achieve good top to bottom support. I don’t like to see toe-out over done and I find it quite frequently gives identical heel and toe cast measurements. On the other hand – and there are always buts with gunfitting – those with very broad chests may need the toe to be brought out a bit extra and may require the toe of the stock to be rounded a little for extra comfort as well as angled out.
Usually a right-hander will require the stock cast to the right – cast-off – and those with broad chests may want more cast than average. Cast can also be used, to a degree, to accommodate differences in facial width and type – a right-hander with a very broad face and wide spaced eyes, for example, may occasionally be seen using a cast-on gun. Off-setting the comb, however, may be a better road to go down in such circumstances. Off-setting the comb has the advantage of altering the rib-eye relationship without putting the butt sole too far out at the shoulder. One may, of course, combine an offset with some cast to reduce the need for extremes of cast.
In fitting for cast, it must be understood that it is not necessarily a question of getting the eye precisely aligned with the rib in the horizontal plane, though this may be used as a starting point for fitting and will be close to the requirement for those with absolute eye dominance in the eye looking down the rib.
Some shooters will need very considerable cast because of eye dominance anomalies. In these cases the eye may be well out of line with the rib when the gun is mounted. Many in middle age may need 1/8 or ¼” extra cast at heel to compensate for the increasing effect of the eye opposite the rib. Cast should always be kept to the minimum possible, as it can increase felt recoil and make a gun feel less natural to point.
I test for cast at the pattern plates, where a tendency to shoot to one side of the mark is usually obvious, and sometimes ‘dry’ with a laser pointing device, such as the Arrow Laser Shot. Cast should be assessed on straight driven and outgoing clay targets. I call the latter ‘the moving pattern plates’ – you can easily identify a tendency to shoot up one side or the other that may be corrected with cast.
Commonly right-handed, middle-aged, men may need a bit of extra cast as the left eye begins to impact more on them – assuming they are shooting with both eyes open. Beware though, cast can increase felt recoil significantly; it puts more strain on a weak area of the stock, and, in its extremes, will hinder natural gun pointing as mentioned. My experience is that extremes of cast should be especially avoided on machine-made over-and-unders.
Very thick combs, as seen on many Continental stock barrels, may unintentionally push the eye to the left of the rib, a simple cure for which is to get a stocker to thin the comb or to fit an adjustable comb and offset it. As well as slimming or tapering the comb, the comb may be ‘swept’ to one side. Both methods can be a useful means of modifying an excessively thick stock – before you consider either, check the butt has not been hollowed to any great extent, or you may pierce the surface of the stock.
As with drop, cast affects the positioning of the gun at the shoulder. It is often said that the butt sole should sit in the so-called ‘shoulder pocket’ between shoulder joint and collarbone. This is not an absolute rule – for some it is the right place, but many successful shots mount the gun on the shoulder joint and would be uncomfortable doing otherwise. What is definitely wrong is to mount the gun on the upper arm, which will not provide consistent support and may lead to bruising injury. One final point: increasing cast may drop the head position slightly just as reducing cast may raise the head position a little.
Alterations for cast and drop are usually made by placing the stock in a jig, heating the grip area by means of hot oil, steam or infrared light and applying pressure in the desired direction. The wood is pushed a little further than required as there is a tendency for it to spring back when it cools. There is always a slight risk to this procedure, and it is greater on guns such as the Perazzi, DT10 and Kemen with detachable trigger groups. You have been warned – bending is always at the client’s risk.
Changes to cast and drop may also be affected by alterations at the ‘head’ of the stock. These involve cutting small amounts of wood from the stock in the area where it meets the back of the action. Many mass-produced stocks benefit from having their combs reshaped by an experienced craftsman, although this will necessitate re-finishing, it is often well worth doing. Some mass-produced guns have club-like stocks with combs that are far too thick and lacking in taper. An excessively thick comb has the same effect as cast and may push the eye out of its ideal position.