Shooting Damascus-Barrelled guns; Sense and Sensibility.

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I know a lot of people online that shoot damascus-barreled shotguns. Some of them shoot thousands of rounds a year, year after year. Yet the conventional wisdom holds that this is inherently unsafe; damascus barrels blow up! Others will reluctantly concede that if you really must shoot these old guns you should only use Black Powder, because modern propellants are stronger than black powder.  That much is true; they are more powerful… but all that really means is that you need to use less of them to produce the same pressure/velocity.

Of course not all black powder is created equal.  Load 3-1/2 drams of FFFFg black powder under a 1-1/4 ounces of shot and you could be courting disaster. The same amount of FFg and shot and it will probably be as safe as anything would be. This is because the smaller grains of FFFFg have more surface area so they ignite more quickly, resulting in higher pressures that build faster.

But smokeless powder has a different pressure curve!  Well, yeah… unless it doesn’t. The following test was performed with modern, state of the art equipment.

“The Double Gun Journal, Volume Seventeen, Issue 4, Winter 2006. “Wall Hanger Rendezvous & The Slow Powder Myth” pages 39-40 by Sherman Bell.

Sherman Bell pressure tested a 1 1/4 ounce load of 3 3/4 drams GOEX FFFg vs. Blue Dot both at 1240fps – results:

@ 1″ from breech – black = 5900psi Blue Dot = 6000psi
@ 6″ from breech – black = 4100psi Blue Dot = 4300psi
@ 12″ from breech – black = 2100psi Blue Dot = 2300psi ”

In the remainder of the article he discusses down-bore pressure curves in detail; it’s worth reading. Back issues can be obtained from http://Doublegun.com

Considering that proof loads run 16,000 to 18,000 psi a difference of two hundred this low in the range is trivial. Several other powders yield similar pressure curves, others- notably powders tailored for pistols- yield higher pressures, but then these are not powders people normally load into shotgun shells.

Manufacturers could and did ‘Nitro Proof’ damascus shotgun barrels. So where did the folklore of damascus barrels being unsafe come from? Well, like any steel these barrels have elastic limits, and if you overcome those the steel will split. Apparently back at the dawn of the twentieth century some reloaders loaded shells with the same volumes of powder they were used to using when they switched to smokeless powder. As noted nitro powders are more powerful, and loading this way could easily produce pressures that could cause a barrel to fail. This was common enough that catalogues and literature of the period specifically warned against this.

Of course any barrel can fail even with safe loads if the barrel is obstructed. A squib load can leave a barrel blocked and if not noted the next shot will almost certainly cause a catastrophic failure.

Another culprit can be extending the chamber to accommodate longer shells- this can place the forcing cone in a thinner, weaker portion of the barrel. Not a good thing. Similarly guns were sometimes over-honed to remove pitting or for some other dubious advantage. If the steel is too thin it’s going to split, no matter what kind it is.

But perhaps the biggest culprit in spreading this rumor were the manufacturers themselves. ‘Fluid steel’ (homogenous steel) barrels were a great deal less expensive to produce, and manufacturers were eager to claim they were an improvement- less because they were than because if they were ‘better’ they could charge the same price that they did for more expensive damascus barrels and thereby increase their profits. There are numerous ads from these manufacturers- who just a decade before had sworn by damascus barrels- that suddenly claimed that they were unsafe. Ah, marketing; thou art a fickle beast.

The last argument I have heard, usually from people that really should know better, is that smokeless powders are unsafe because they are a ‘High Explosive.’ A high explosive has a burn-rate that exceeds the speed of sound. Touch it off and it goes BOOM even if in an open, unconfined area. Smokeless powders have combustion inhibitors to prevent them from doing this. They are most definitely not high explosives.

This is not to say that all guns are safe with all loads, and any 100 year old gun should be carefully evaluated before firing it. It is also prudent to restrict these old guns to low-pressure loads, though less because of concerns about splitting the barrels than to avoid accelerating wear on a gun that has already had a full working life- or two, or three. Any antique firearm should be carefully inspected, ideally by a competent gunsmith, before use.

Honestly while I could tell you how to test an antique I dare not. In this litigious age if someone was injured through mis-applying those instructions I could easily be sued. I can tell you a few things to check to see if it is worth having it examined by a competent gunsmith. Examine the bores inside and out. If it is severely pitted, if there are any visible rings, bulges or dents you have a problem. If the barrels are loose on the frame when locked you have a problem. If you separate the barrels and ‘ring’ them you should not hear any vibration or buzzing; this would indicate that the rib was separating from the barrels. Not only is this commonly caused by bulging a barrel, it can allow moisture to enter and corrode the barrels unseen. Examine the rib and make sure there are no gaps in the solder for the same reason. If the gun appears sound by this inspection it could be worth actually paying someone to examine it further.

One thing to check is the chamber length- in some gauges standard shells were shorter than today’s ammunition, and using modern-length shells can cause an unsafe pressure condition in these old guns. A gunsmith can determine this for you. This doesn’t mean that you cannot use the gun; if there is enough metal ahead of the chamber a gunsmith can lengthen the chamber for you. Another option is to load your own ammunition to the proper length.

Damascus, Fluid Steel or whatever, respect the gun, it’s limitations, your own safety and that of those around you. If you have any doubts, well, it’s far less troublesome to consign a gun to ornamental status than it is to live without a hand or an eye.

Addendum: RST specializes in low-pressure shells, including 2, 2-1/2 and 2-3/4 inch shells specifically for use in old guns. http://www.rstshells.com/store/default.aspx

 

 

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