How to blow up a rifle - Handloader

Guns Magazine, Sept, 2003 by Charles E. Petty

One part of my work that truly fascinates me, is the examination of firearms that have failed catastrophically. They almost always have a story that may not be supported by observable facts -- you know -- the dog ate my homework sort of stuff, but the painful truth is weird harmonics or powder detonation which often get blamed don't have much in the way of science to support the story.

Examination will usually show that excess pressure is the cause. And more often than not the hand-loader, not the butler, "done it." Very often the story has lots of, "I don't know" lines followed by, "I couldn't have done" this or that. So when we find a hand-loader who not only figures out what happened, but is honest enough to admit it, this is a golden opportunity to learn.

"Bring Your Camera"

It all began with a call from a local gunsmith who suggested a visit might be in order. "Bring your camera," he said. When I got there I found a Howa 1500 action that had been fitted with a custom barrel in 6.5-'06. Actually there were 29 pieces of it. Not too long ago a buddy came up with a new acronym that perfectly describes the condition: SCLID. Which stands for Spontaneous Catastrophic Load Induced Disassembly.

The receiver ring was split into two parts leaving the barrel completely separate. One receiver rail was turned at a 90-degree angle away from the bolt, but perhaps the most noticeable thing was the deposition of brass along the bolt and deep into the hole where the extractor used to be. Much to my surprise, the remnant of the cartridge case was still in the chamber although there was a substantial portion of the base missing, some of which was deposited on the bolt.

Sequence Of Destruction

Most of the other pieces were there and when laid out in the proper order you could clearly see how it came apart. The initial failure was obviously the cartridge case and it ruptured at about 3 o'clock, which is the area right under the extractor. Since this is the part with most clearance, the case began to expand toward the path of least resistance.

With the extractor blown away the pressure peeled the receiver rail back to the right and, at the same time, split the receiver ring in two in an upward direction. Laying the parts back together as closely as possible you really could see the progress of the destruction although it would have seemed instantaneous to an observer.

After I had studied the wreck awhile the gunsmith told me the rest of the story. The owner needed to fireform some new brass and went to a local indoor range capable of handling major centerfire rifle calibers. The 6.5-'06 is a simple wildcat made by necking the old .30-'06 down to 6.5mm and fireforming. That procedure is usually done with a fairly mild load -- somewhere in the starting range of loading data.

He had done this before and settled on a load of 46.0-grains of H-414 and a 120-grain bullet. He reports that the first shot produced the wreck you see here, and he was left holding only the butt portion of the stock. The barrel was approximately 10 feet downrange. The shooter was uninjured but one lens of his shooting glasses was severely pitted and almost surely prevented an eye injury.

Detective Work

Most of the pieces were retrieved and the shooter set about finding out what went wrong. It wasn't hard. He had made one of the most human of errors. Instead of the H-414 he wanted, he picked up H-4227 and loaded the cases with 46.0 grains of it. The magnitude of the error is huge. On a recent burning rate chart H-414 is number 95 on a list that goes from 1 to 122. The order is from fastest to slowest. H-4227 sits at number 56. Even though there is a similarity between the package labels the powders themselves could hardly be more different. H-414 is a dark spherical (ball type) powder while H-4227 is a small grain extruded type.

Using the Quickload computer program I estimated the pressure of the destructive load at over 107,000 psi. That's more than twice that of an average high-intensity centerfire cartridge and more than enough to cause the damage seen here.

This is a great opportunity to learn something and, since all good stories have morals, there are a couple here. This is almost one of those, "there but for the grace of God go I" events, for I know I have picked up the wrong can a time or two. I'm sure he was in a hurry and got on "autopilot" to crank out a few rounds. So the first lesson is to always double-check everything.

But the most important lesson comes from the example the shooter gave us. He figured out what was wrong and owned up to his mistake. He didn't make excuses or try to find somebody to sue. Rather, he took responsibility for his own actions.

And, since clouds sometimes have silver linings, there's one here. The way the case and action failed turned the barrel loose early in the sequence of events so, with the exception of a couple of dings where it bounced on the concrete, the expensive custom barrel is unhurt. It is most common to see chambers that look egg-shaped after events like this but careful measurement found nothing out of specifications. I suspect that the gunsmith will set it back a couple of threads to get a clean new chamber, but he could also just screw it into a new action and carry on.