The essential guide to boxlocks, sidelocks and sideplates

What’s in the box? Richard Atkins asks: Do you know your boxlock from your sidelock or sideplate?

The Yildiz Pro is a refined and well-built boxlock action that also has a remarkably competitive
price tag of £2,250

While many shooters aspire to own a ‘better’ gun than they started clay shooting with – probably one with an established brand name and a cult following – it is common to start with something less exotic and, more importantly, less expensive.

So what is it that separates the budget guns from those perceived to be better? There are differences of course, but they may not be the ones that the typical buyer thinks about when making their purchase.

A key feature of any shotgun is the quality of the trigger pulls. I’m frequently surprised by how many shooters don’t fully understand this (as can readily be seen by comments made on social media sites).

Things are relatively straightforward for the game shooter choosing their side-by-side. Although there are plenty of variations to be found, most side-by-side shotguns are either boxlock or sidelock actions. Boxlocks are usually based on the simple but robust Anson & Deeley design, which allows strong, competent guns to be built at affordable prices. Sidelocks often follow the London seven-pin or nine-pin designs, but the gunsmiths’ ingenuity means there are other derivative designs to be found too.

Taking these two action types – which also exist in over-and-under guns – there are features that make them differ in performance and price. The essential difference is that boxlocks are simple and sidelocks are fairly complex. But why so? What is the point of making a complex action when a simple, much cheaper option exists?

The Yildiz Pro bases its action design on the Boss action, and its trigger pulls proved light and crisp when on test

It would take a good book to explore this question fully, but we only need consider the essentials here. In its simplicity, the boxlock action can be made quite crudely and cheaply. At this level, where there is no financial leeway for finely machined and hand-fitted parts, boxlock actions provide serviceable, robust and usually very reliable actions. But the cheapest lack both refinement and some features included with more expensive types.

While all manufacturers today provide the basic safety we all demand, the most obvious weak point in the cheapest boxlock actions is the quality of their trigger pulls (or lack thereof).

There are, unfortunately, plenty of shooters who do not fully appreciate the difference between the sometimes long and heavy trigger pulls of cheap guns and the much more user-friendly trigger pulls of an expensive and refined action.

Through many years testing a wide range of guns, including all types of shotgun (and much else besides, from match air pistols and air rifles to handguns and fullbore rifles), I have encountered trigger pulls of all types. As a result, I’m acutely aware of the difference good trigger pulls can make. I offer this advice to anyone setting out to buy a shotgun, whether for clay shooting or game: once you’ve established a basic gun fit to attract your interest in a gun, ask for some snap caps so you can try its trigger pulls. If your early attempts to fire the gun leave you wondering if the safety catch is still applied, then that gun may not be for you.

Make or break

The beautiful Beretta SO 10 is an exquisitely built sidelock and offers trigger pull qualities that cannot be bettered, but at a cost of £50,000 plus

Heavy trigger pulls can easily make or break shooting performance. A long and heavy trigger release, with too much drag, can be ruinous because it makes it impossible to time your shots as you should. Sadly, I still meet shooters who don’t seem to realise this and who carry on unaware of the cause of their erratic results from one day to another, and it can often feel as though the clays are made from aluminium some days, or else wearing flak jackets.

The primary problem is that too much weight is required to release the trigger. If your gun can produce the ‘safety catch still on’ feeling, chances are you will often pull your barrels off-line at the crucial moment, with obvious results. But not everyone affected realises that this is happening to them. Having someone stand behind you while you shoot a few crossing clays will soon show if it is happening to you.

Not all budget guns have such poor trigger pulls, but few have particularly good ones. I bought one of the first ATA SP over-and-under guns sold in the UK. The trigger pulls were usable but, as I wrote in my review at the time, were heavier than my preference. A modest amount of money spent with my local gunsmith made the trigger pulls much nicer – still not in the realms of a Beretta SO, Blaser F3, Perazzi or Zoli Z gun, but it was a fraction of the price you’d pay for those. The work made a budget gun into something more than that, and my gunsmith put in the time to set things correctly – a service that no budget maker can include for the price.

Of course, there’s a limit to how much trigger pulls can be improved on a budget gun. Nonetheless, as boxlock guns are by far the majority, it’s as well to become more aware of their strengths and weaknesses. There are key reasons why budget guns tend to have less refined trigger pulls, and they all stem from one obvious factor: cost.

Although not externally evident, the design of budget guns is necessarily more basic than that of their more expensive counterparts. The materials used will usually differ too. Today, there are several new methods of producing the intricate parts of a shotgun, such as MIM and Investment Castings, which are now widely used for gun components like the receiver body and most action internals.

Both of these methods allow parts such as tumblers (‘hammers’), sears, trigger bars, sear lifters and recoil blocks to be used almost straight out of the cast or mould. Some parts require only a light tumbling in a polishing medium, while others may need light linishing on one or two faces, but crucially they do not require the time-consuming and expensive process of being machined through multiple procedures from a piece of high-grade steel. A single part that once cost many pounds can now be produced for a fraction of the cost.

The differences between budget gun actions and those of higher-grade guns should be clear from these images. The Lanber Sporting Lux is a sound, basic design typical of guns around the £1,000 mark

The designs of these actions are simplified too, so they can be quickly built to give reliable performance without hours of hand fitting by a craftsman.

To ensure reliable and, above all, safe functioning, it is usually necessary to make the engagement points of the sear and bent deeper than is strictly necessary. When no one is tasked with the time-consuming work involved in fitting and polishing the sear/bent engagement you get with more expensive guns, the only way to ensure a safe trigger release is to err on the side of a deeper engagement and heavier pull release weight. This cannot be done any other way, and it still produces a safe and reliable gun for a budget price. However, you only need to read a few comments on shooting forums to see that there are people who sadly don’t understand this.

To fully appreciate what I have tried to explain here, look at the photographs in this article, which show just how small the degree of engagement between the sear and bent can be. That this tiny engagement is all that holds back the tumblers that are released to discharge the cartridge may surprise some gun owners (even some experienced ones).

A fine balance has to be reached between a gun that will not discharge accidentally when it is jarred or dropped, and one that has an acceptable trigger release. In my experience, only a few shooters today realise just how tiny the material contact point is that decides whether the gun fires or not.

Another factor that influences trigger weight, especially with gun parts made by fast, modern methods, is that the materials used are not the same as when parts are machined from selected blocks of solid steel sheets or forgings. Quite high forces are encountered at the contact points between sear and bent each time the trigger is pulled. This intense pressure wears the engagement faces over time, and much faster on some materials than others. The end result is that many budget guns cannot safely have their trigger pulls lightened to match those of a superior grade of gun, because the engagement tips will wear more quickly, or even break off, resulting in a greater chance of inadvertent discharge.

Sidelock features

Sidelock actions are much more complex than any boxlock. Instead of a set of parts housed within a framework (or ‘box’) at the rear of the receiver, sidelock guns have two complete and quite separate actions, one on each side of the receiver body. These are set into the receiver and, although they may have cross bolts joining them, can be easily removed for cleaning, adjustment or repair.

The sidelock design allows a very precise geometry for the engagement and disengagement of sears and bents, providing some of the most exquisite trigger pulls to be found on any shotgun. It’s also usual for the design to include ‘intercepting sears’. Should a gun with this feature suffer a jar or shock that causes the sear to disengage from the bent, the intercepting sear will prevent the tumbler striking the firing pin unless the trigger has also been pulled. This prevents accidental discharge.

As with most things, there are variations. Some makers offer budget sidelocks, which may not have the refinement to include the intercepting safety sears. Better a well-made boxlock than a cheap sidelock. But done well, sidelocks offer the opportunity for very good trigger pulls with optimum safety.

A side-plated gun is not a sidelock

Without going into more details, it should suffice to point out that, although they look very similar, a side-plated gun is not a sidelock. It is in fact just a standard boxlock action to which side plates have been added. If done well, this can add strength to the stock where it joins the receiver. But if less well done it may do the opposite. The prime advantage of side plates is to provide a lot more room for the engraver to show off his or her art.

Zoli’s Z gun is a good example of a detachable trigger mechanism. It falls between the Yildiz Pro and the Beretta SO 10, with a price tag in the region of £8,500 to £14,000 according to exact model

Detachable trigger units

A common feature among several makers of high-grade competition clay target shotguns is the detachable trigger. This is what the ‘DT’ in Beretta DT10 and DT11 refers to. These are a hybrid action in which a more refined boxlock design is housed within its own, separate frame that can be inserted and removed from the receiver body. This tends to make guns a little thicker in the hand of the pistol grip, as the receiver must have a framework for the action/trigger unit to lock into.

Actions of this type are more refined than conventional boxlocks and invariably have excellent trigger pulls. Being removable, they can be cleaned, adjusted and repaired almost as easily as a sidelock.

Safety sears and bents

Some of the better boxlock designs and, as far as I am aware, most detachable trigger guns, have safety sears and bents that replicate the duty performed by intercepting sears in the sidelock. In its simplest form, this is achieved by having a second, much deeper bent cut into the tumbler, with the normal sear being spring loaded. Should the tumbler drop because of jarring, the sprung sear engages with the bigger secondary bent behind the primary bent. The geometry of the sear/bent relationship is such that the second or ‘safety’ sear is not engaged when the trigger has been pulled as intended.


These are the primary action types in basic outline. Perhaps they will help make a more informed choice with any future buys. And, just maybe, those who think there is no good reason why two similar-looking guns, but with one twice the price, will have a little more understanding as to why the actions are not the same. Similar factors affect other components but that is for another day.

More essential guides

This article originally appeared in the May 2018 issue of Clay Shooting magazine. For more great content like this, subscribe today at our secure online store

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Posted in Advice and tips, Ask the Experts, Coaching

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