Visiting Gavin Gardiner while he was preparing for his August Gleneagles auction, he passed me a 12-bore hammer gun by Edward Paton, a good gunmaker from Perth. First of all I noticed the apparently swamped rib with the odd-looking visible breech face. Next, I was drawn to the absence of a bottom rib. Then the penny dropped; the barrels were made from a single piece of steel, including the central ‘rib’, and were engraved ‘Joseph Whitworth & Co.’

Shirley Bassey’s History Repeating started playing in my head as I mentally linked the Paton with the new Longthorne O/U that I had seen recently, which features one-piece barrels. It seems that history is repeating itself.

Joseph Whitworth is well known to gun collectors for his steel tubes and his rifling. He was an engineer who brought mechanisation to many craft processes and so helped modernise British gunmaking. Damascus barrels had been used since the days of flintlock, but quality control had always been a problem and craft techniques in a mechanical age were outdated. The problem with using early homogenous steels was in the process for casting ductile steel: it tended to leave air pockets, making the steel weak. Whitworth’s patented 1874 solution was an adaptation of Bessemer’s principle of hydraulic pressure casting and is the reason we see many old gun barrels inscribed: ‘Made from Sir Joseph Whitworth’s fluid-pressed steel.’ Whitworth’s earlier patent, number 1645 of June 1857, is unknown to most people. It refers to milling two barrels from a single piece of fluid steel. The process leaves the two tubes joined by a thin central rib.

In the Paton gun, the top rib is laid only at the muzzle, to site the bead. The proof marks are London and denote pre-1875 proof as a 12-bore. The Paton records do not help much, only indicating manufacture between 1875 and 1887.

Gavin Gardiner catalogued the gun with the following note: the gun has one-piece barrels made by Sir Joseph Whitworth, patent number 1645 of 1857. Taking into account that Whitworth was knighted in 1869 and later barrels referred to ‘Sir Joseph Whitworth’ and that Joseph Whitworth & Co. was formed in 1874, we can deduce that the Paton’s barrels were probably made around 1874, using Whitworth fluid-pressed steel and his 1857 patent.

So if a single-piece barrel is such a good idea – strong but light – why did it not become more popular? Longthorne Gunmakers tells me it is a combination of high cost and the inferior materials available in the mid 19th-century. Longthorne’s gun barrels are made from much harder steel than Whitworth had available. Today, with more sophisticated machinery and better materials, Longthorne claims to have made Whitworth’s 1857 idea practicable and cost effective: the 30” barrels weigh just 47oz with �” chokes and a minimum wall thickness of 37 thou’. But what was so good about the idea in the first place?

Traditional barrels are made from two tubes with either dovetail or chopper-lump construction. The ribs and loop are then soft-soldered in place. The potential weaknesses are at the points of assembly: dovetail lumps can work loose, as can loops; solder can fail and allow moisture to collect, rusting the barrels from the hidden valley between them; ribs can come loose; the ribs and solder add weight to the barrels; and the various heat treatments applied when brazing, soldering and fitting barrels can affect the straightness of the tubes.

A one-piece construction avoids all these problems, according to Longthorne, and the benefits of straight tubes are a reduction in recoil and shot patterns which converge much better.

Traditional barrel makers are sceptical. One told me: “They [Longthorne’s barrels] don’t have the feel or look of hand-made barrels. It is a machined job. The barrels are all made the same and cut to whatever length is required; convergence and regulation can’t match traditional barrels.”

The much-celebrated Sir Joseph Whitworth was a man well ahead of his time, in gunmaking and other industrial disciplines. It was a fascinating experience to link his idea, dating from the year in which Darwin published his treatise on evolution, with the cutting-edge gun-making technology operating in Britain today. The Paton hammer gun with Whitworth barrels and the modern Longthorne O/U are cousins.

The jury remains out on one-piece barrels. I will watch with interest to see if other gunmakers accept the revised process and we see it rolled out elsewhere in the trade, or if this second wave of one-piece barrels eventually founders like the first did, sometime before 1880. As always, time will tell.

As for the rare Paton with the Whitworth barrels, Gavin offered it up with an estimate of �2,000-�3,000 and got it spot on; the gun made �2,600 and will become a unique part of someone’s collection.