The double barrel shot gun is growing in popularity, now that almost no one makes one and the average shooter can not afforded those few doubles that are being made.. Old doubles, as we affectionately call them, are increasingly collectable and growing in value. When we handle an old double we often think, how would it be to shoot this gun, and is it really safe to shoot? I used to have a rather cavalier attitude about shooting old doubles, but an incident a couple of years ago changed my mind. As one of the authors of the forthcoming book, The Parker Story, I was making frequent trips to Remington in Ilion, N.Y. During one of these visits I was shown a blown up Parker Bros. gun, Vulcan grade. The explosion had separated the right barrel from the left, and the last twelve inches of the breech end of the right barrel was in four pieces. The force of the explosion had sheared off the right leg of the frame just under the standing breach. The forearm wood was a collection of splinters. No one could give me the complete story about what had happened. Apparently the remains had been sent to Remington by someone. As far as anyone knew, the only explanation coming with the gun was that the shooter had been using reloads. Nobody could tell me how seriously the shooter was hurt, but looking at the remains of this gun you knew his injuries had to be serious. Since then I have been more careful about which doubles I shoot and what shells I use in them. Let's examine some of the standard responses given to the question "is it safe to shoot?"
The most common response is If the barrels are fluid steel it is safe to shoot and if they are composition, such as damascus or twist, they are unsafe to shoot.. WRONG! A FLUID STEEL BARREL IS NOT NECESSARILY STRONGER THAN A COMPOSITION BARREL! John Brindle wrote about this in his excellent five part article in the Double Gun Journal , volume 4 issues 2 & 3, summer & fall 1993 , and volume 5 issues 1, 2 & 3. spring, summer and autumn 1994, in an article entitled BLACK AND NITRO, DAMASCUS & STEEL. In this series he cites the tests conducted by the Birmingham Proof House in 1888. Thirty nine different types of barrels, three examples for each type, were tested with increasing loads until a bulge of 0.01 inch or a burst occurred. The top four strongest barrels were, 1. English machine forged laminated steel, in three rods [a composition barrel], 2. English fluid compressed steel, Whitworth process [a fluid steel barrel], 3. English machine forged Best Damascus in 2 rods [a composition barrel], 4. English steel Siemens - Martin process [a fluid steel barrel]. The balance of the list showed a similar distribution between fluid and composition steel barrels. Composition barrels, however, are a mass of welds and because of the pattern in them ,it is almost impossible to spot a weld that now has corrosion in it or is beginning to open up. The only sure way to test the soundness of a composition barrel is to have it Magna fluxed. It is only with age that the fluid steel barrel becomes safer than the composition steel barrel.
Another common response, in the case of foreign proofed doubles, is If the barrels are marked NITRO they are safe to shoot. NOT NECESSARILY SO! EUROPEAN DOUBLES, IF IN GOOD CONDITION, ARE ONLY SAFE TO SHOOT WITH THE LOADS FOR WHICH THEY WERE BUILT! The book, THE STANDARD DIRECTORY OF PROOF MARKS, by Wirnsberger and Steindler give the pressures to which proofed guns were subjected to in order to pass proof. For example, under the 1912 rules, German 16 gauge guns marked NITRO were subjected to a proof pressure of 12,800 psi. This does not mean you can fire any shell in these guns that does not exceed peak pressures of 12,800 psi. When a shot gun barrel is fired it expands and then contracts, hopefully, back to its original dimensions. Over the years this expansion and contraction weakens these barrels. Most guns, used extensively over the years, will probably not pass those same proof tests today. Also, the average load for a 16 gauge gun in the pre WWII period did not exceed 8,000 psi. peak pressure. Wirnsberger and Steindler state, in the case of German guns, "a shotgun with 2 3/4 inch chambers and an American shell containing over 55.5 grains or 1 1/4 ounces of shot for a 12 gauge gun or a 1 ounce load for a 16 gauge gun should not be used except in those instances where guns have undergone special proof." Back in 1960, when I had a growing family and few dollars, I bought a WWI vintage 16 gauge German double that was NITRO proofed and had only 2 1/2 inch chambers. I lengthened these to 2 3/4 and fired about a box of low brass shells in the gun. After the first box I had second thoughts about what I had done and retired the gun and never fired it again. When thinking back on this, I probably would have been safe if the gun originally had 2 3/4 inch chambers and I had confirmed with the manufacturer that the low brass shells I was using did not develop peak pressures in excess of 8,000 psi.
The most correct response is Let your gunsmith look over the gun. If he tells you it is safe to shoot then you can shoot it. NOT ENTIRELY CORRECT, BUT THE BEST RESPONSE! Not every gunsmith has all the knowledge required to insure your safety. Among the things a gunsmith will do is measure your chambers for length and diameter to see if they are still factory standard. Doubles, early in this century, had chambers that were 2 1/2" long (marked with a 65 in the case of European guns) ; later, 2 9/16" and finally today's standard of 2 3/4"(marked as 70 on European guns). Some of these early guns may have had their chambers lengthened. This weakens the barrels. Still others may have had a long forcing cone reamed into them. This further weakens the barrels. The problem here is that not every gunsmith knows what the original factory standards were. He will also measure the bore to insure it is still standard and has not been back bored to remove pitting and corrosion. He will then measure the outside of the barrels to insure there are no bulges. A bulge of 0.01" distributed around the circumference of the barrel, and cause for failure in the 1888 Birmingham tests, is less than the thickness of a sheet of newspaper and not detectable by eye alone. The one area he can't examine is that under the ribs and between the barrels. When the two barrels are joined the mating parts are treated with acid to clean them, and then tinned. The barrels and ribs are then wired together and the assembly placed in a gas furnace to heat the barrels to the melting point of the solder. When cool, the barrels are then cleaned of excess solder and acid. However there is no way to remove the acid between the barrels. This is not a problem unless the mating of the barrels and ribs is not airtight. If a rib should become loose moisture will seep into this cavity, mix with the acid residue and create rust. Over the years I have separated a number of barrels and found severe rust and corrosion between some of them. So, I stay away from guns with loose ribs or vent holes in the rib. It is also important to insure that the barrels lock up tightly to the face of the standing breech. Any play here amounts to excessive headspace which results in a hard kicking gun and increased peak pressures. A gunsmith can give your gun a reasonable bill of health regarding its safety, but, not an absolute guarantee!
So, what should one do?". After 67 years of seeing out of both eyes and having gotten used to having five fully functioning fingers on each hand, I have adopted a rather-safe-than-sorry attitude. As a general rule, I no longer fire any double made before WWII. I have one exception to this rule and it is my French Darne in 16 gauge. This gun is marked as being double proofed, which at the time was a proof of 20,495 psi., far more than any current 16 gauge shell will develop.
What would I do if I were younger and more adventurous? Well, I would first of all have the gun evaluated by a competent gunsmith. If it passed his inspection, I would research the proof the gun had undergone. If it was proofed for black powder, I would only shoot black powder in it. I would invest in reloading tools and make up my own loads. I would insure that my shells were the proper length for the chamber. I would start my loads at about 50% of the equivalent of the proof load given in The Standard Dictionary of Proof Marks. I would gradually increase this to no more than 65% of the original proof load. I would also make sure that I always wore my shooting glasses when firing these guns. What about American made guns with original 2 3/4 " chambers? There is no way of telling what pressures these guns were subjected to during proof, as most of those companies are now defunct and records lost. There are Parkers, L.C. Smiths, Ithacas and other well known makes being shot every day with currently manufactured ammunition. With few exceptions (like the Parker story related above), there have been no disastrous incidents. These guns will probably continue to be safe with standard loads, for many years to come. However, they were never designed to handle Magnum or Long Range loads and to use those in these guns is inviting disaster! Even if the gun doesn't blow up, the pounding of these heavy loads will cause the gun to shoot loose and stocks to crack. If you want to shoot these heavy loads, make sure the gun you use was specifically designed to handle that load.
In summary, any double in fine condition is safe to shoot only with the loads for which the gun was built. Remember, you can't replace the sight lost from a damaged eye, so only shoot those guns and loads that were meant to be used together!