The images below depict a Smith & Wesson Model 629 .44 Magnum with 6½ inch barrel that has been the victim of a rare phenomenon known as an integral detonation.

A detonation is an explosion that blows the gun apart instead of firing the bullet down the barrel. This occurs when the gun is initially fired.


It is thought that a detonation occurs when instead of the cartridges powder burning evenly from the rear of the cartridge to the front to fire the bullet, it detonates all in one go.

Exploding rather like C4 high explosive.  This can actually occur any time a weapon is fired but luckily it is very rare for it to do so, literally one in a million.

The science behind this effect is not truly understood but it is believed that when the cartridges primer is struck by the firing pin and it ignites, the resulting flash jumps over the powder in the cartridge and ignites if from the front as well as the back to meet up in the middle.

Obviously the mechanism of a bullet being fired from the fall of the hammer to the bullet exiting the barrel happens in milli-micro seconds.



The resulting force which is measured in the tons per square inch, is sufficient to blow the cartridge apart, taking with it the encapsulating cylinder.  Sometimes, as seen here, adjacent cartridges can also explode with the terrific force of the ensuing explosion.

The top of the cylinder and the frame of this revolver have been completely blown away, the explosion would have been extremely violent to have resulted in this way and the shooter would have been lucky not to have been injured.  I understand he received a flying shrapnel gash across the forehead, luckily not life threatening.

On the firing range, shooters must always wear shooting glasses and ear defenders to offer protection from flying shrapnel, burnt powder and the noise these things make when fired. This exploding revolver illustrates the need for personal protection very well indeed.

It is evident that an integral detonation in the cylinder rather than an obstruction up the barrel caused this damage, as there is no bulge in the barrel.  A bulged barrel is always a clear sign of an obstruction, as when a bullet hits it at 1500 feet per second then the barrel bulges, the barrel can also disintegrate.


These close up images show the total devastation.  You might notice the bullet in the adjacent cylinder has actually fired forward, just as the cartridge exploded via the chain reaction of the initial explosion.

As the force went upwards instead of forwards the bullet was not fired, it would not have had a clean line of exit anyway as it was not lined up with the breach.



It still may be stipulated that the cartridge was overcharged with powder to have exploded/detonated like this, or faulty workmanship of the gun itself is to blame.

These are the common reactions, however, revolvers such as the big .44 Magnum are exceedingly strong and are factory proofed before being sold.

Proofing a gun ensures that even if they are  overcharged they cannot or at least should not  explode.  A detonation however is a different kettle of fish, the gun will  explode/detonate almost as if an explosive charge of C4 was inside the cylinder of the gun.

I would like to state here that it is still possible to blow a gun apart with an incorrect or overcharged measure of powder, but its not common.  I would also like to reiterate that a detonation like this is extremely rare and not an everyday occurrence.

The metallurgic properties that goes into making handguns is a science in itself, to ensure the safety of the shooter.



A guy recently sent me some images of his .44 Magnum that exploded when he fired it out on the range.  It looks like a classic case of a detonation, the gun was blown apart.

Luckily, the shooter got away without a scratch, as most of the force went upwards and to the sides...away from the shooters hand.



It was Model 629 Smith & Wesson Stealth Hunter,  with a Performance Center  six inch weighted barrel, fitted with SpeedDot-135  by Burris, telescopic sights.  Unfortunately the sights were also damaged in the resulting explosion.



The bullet that was to be fired was a hand loaded round with 7.5 grains of Universal powder and a 260 grain LSWC Keith style bullet.

Because the bullets were meticulously hand loaded by an experienced shooter, we know it was not an overloaded cartridge that exploded.  Hence it had to be a detonation...the jury is not out on this one!



Apparently, it was the ninth round to be fired out of ten test loads. All the rounds fired previously were chronographed and averaging 995 feet per second. Hence these were moderate loads to be fired for a .44 Magnum and were not "powered up" in any sense of the word.

Below is a close up of the explosion, a bullet can still be seen in the remains of the cylinder.  Also notice how the explosion blew out one of the cartridges spent primers, the cylinder blew up like a hand grenade going off.



This may be another good reason why it is a good idea to have your guns insured, as this was an expensive catastrophic failure.  The gun is a total write off, this sort of damage cannot be repaired due to the stresses involved when the gun is fired. Therefore, a new cylinder, a new frame and possibly a new barrel would be required, hence a complete gun.

Photo credits go to the guns owner, Arch Wingo.  Thank you for sending them in.




page created June 6th 2010.    Updated January 8th 2013.