The basics of stock dimensions, what you need to know, where the measurements are found on the gun and why they matter.
One of the most common things folks do when inspecting a potential shotgun purchase is shoulder the gun. It seems an interesting thing that ‘gun mount’ is such a crucial part of the gun purchase, but so many folks simply shoulder a gun and assign a non-quantitative value to it: “oh this shoulders nice” or “feels right”. So many of those folks realize that a gun must ‘fit’ but very few actually know or understand their own stock dimensions and how they translate to a gunstock. The same holds true for backyard clays shooting when you try a new-to-you shotgun that seems to break everything at which you point. In those situations gun fit and by association stock dimensions are at the heart of the matter.
Length of Pull
The most basic of stock dimensions and one that is actually addressed by some gun companies is the Length of Pull or LOP (as it appears on many online gun listings). The length of pull is the distance from the center of the (front) trigger, rearward to the center of the butt plate or pad. This is also expounded upon at times with three different LOP measures: LOP to the heel, center, and toe. The comb is the top of the stock, where your cheek rests which terminates at the heel, while the toe is the bottom portion of the end of the stock. It is typically tapered and comes to a point. LOP to the center determines the primary contact between shooter and buttstock, but the heel and toe measures give an idea of the stock’s pitch.
Pitch is the angle between a line defined by the rib (and/or comb) and the line defined by the butt (given that the butt is not curved). If you imagine laying the long leg of a square on the rib, the 90-degree angle defined by the square would be pitch. This angle can obviously be greater or less than 90 depending on the shooter’s preference or the gun’s intended use. Typically pitch is adjusted for guns that will shoot driven birds; all overhead shooting where the gun is pointed primarily up versus rough shooting where shots are out in front of the shooter. Pitch can also be adjusted so that the toe of the shotgun does not dig into a shooter’s chest. Shooters with fuller chest dimensions will oft times complain about this digging of the toe.
LOP is important because it determines the geometry of the shooter’s arms. A short LOP will ‘chicken-wing’ your arms; the angle at your elbows being very acute. A long LOP will open up the angle of your arms and in extreme cases even straighten out the arms. The goal here is to adjust the LOP to create a proper geometry between the shooter and the shotgun or rifle in question. There is of course a sweet spot where the shooter’s arms are comfortable and provide the most stable and controlled connection between the gun and body.
LOP is addressed by some companies who typically include a basic thin wooden or black butt plate with their guns. The idea behind this is that they leave as much stock wood as possible by only adding a thin pad. Then the shooter can add a 1” or larger recoil pad to increase LOP or cut the stock down and add a pad to decrease LOP. Other instances like youth guns for example typically have shorter LOP to fit youth shooters.
Drop at Nose, Drop at Comb (Face) and Drop at Heel
Two other primary stock dimensions are drop and cast. Drop addresses the relation of the comb to the rib up and down, where cast determines the relation of the comb and rib left to right. Drop on a stock comes in two (sometimes three) measurements and they are usually listed in order from the nose or most forward part of the comb to the heel. The measurement is actually the distance from the line defined by the rib (and parallel to the bores), to the spot on the comb being measured. One can get rough stock dimensions of drop by placing a shotgun upside down on its barrels (and thus the rib) and taking the measure from the comb to the tabletop. These measurements are complicated by monte carlo stocks with elevated cheek pieces, which sometimes have drop measurements for each end of the raised cheek or monte carlo piece, as this is where the shooter’s cheek contacts the stock and in effect is the important factor in drop. Proper drop will position the shooter’s eye in line with the rib. Too much drop and your eye will be below the barrels and when your face is properly against the stock, you will be looking at the breech of the gun. Too little drop and you will be looking down at the rib, seeing the entire length of it while shooting.
Too much drop requires the shooter to lift their cheek off the stock to appropriately sight down the rib. Though this can be done, it is no longer in vogue. The old style of head-held high shooting has gone by the wayside as folks have moved into more modern styles dictated by sporting clays and other shotgun sports, though this old shooting is immortalized by our favorite shooting artists in many of their classic pieces. Too little drop is very hard to adjust for because you can’t ever get your eye properly in line with the rib, so the gun will always shoot high.
Cast On or Cast Off
Cast in a stock is dictated by the shooter’s dominant hand/shooting side, and by their physical stature. Guns can be cast on or cast off. I always remember it (I am a right-handed shooter) that when I mount a gun, a stock with cast ON will be ‘on me’ or closer to me. A gun with cast off will be ‘off me’ or away from me. When one sights down the rib of a gun from the muzzle (a double-checked unloaded and safe gun) standard stocks will generally be neutral cast; the comb aligns with the rib. Guns that have cast will either have the comb of the stock to the left or right. This is in effect a slight bend in the stock that generally happens in the wrist. This bend could be just that, an actual bend where the stock was steamed and put into a fixture to impart the bend, or shaped into place when the stock was made by a stockmaker. This cast is typically given as a single measure taken from the comb, but again there can be measures for the cast at the heel and toe. A cast difference between heel and toe can dictate a twist in the stock. Again, for fuller figured folks, a gun with the toe cast further off than the heel will help eliminate uncomfortable toe digging into the chest.
Typically a gun with cast off would allow better alignment with the right/dominant eye and the rib. When you lay your cheek on the comb, your eye typically is offset to the line of the comb. For a right handed shooter the eye typically lands a bit to the left of the comb, and a cast ‘off’ or away will allow the eye to come back to the center of the rib. This bend keeps the shooter from having to roll their head over the stock to get proper eye alignment. Cast on is generally the proper dimension for a lefty. Though all of these are generally speaking. Righty shooters with fuller faces need more cast and those that are skinnier need less and so on.
There are additional stock dimensions and features if one wants to dive into the minutia of detail. For most though, an understanding of these basics should help the next time you are considering a gun purchase. And of course, like patterning your shotgun, the effectiveness of shooting skeet chokes, or the cadre of other things I harp on, nothing can replace a gun fit done by a professional. Even if you don’t plan on having a stock made for you or having one bent to your specification, simply knowing your stock dimensions may help tip the scales the next time you are faced with the age-old question of whether to buy or not to buy that next shotgun.