Burst Ruger Carbines

[JimInNJ]

A friend at one of the local PDs was telling me that both his department and a neighboring municapality have blown up Ruger carbines by mistakenly loading 9mm ammo in weapons chambered for .40 S&W.

Apparently the 9mm rounds fit the magazine, fired and cycled the action, but from what he discribed the first bullet must have wedged itself in the bore just short of exiting.  Theirs balooned and burst the barrel near the muzzle on the 2nd shot.  The other department's burst at the breach and they found quite a few bullets stacked up in the barrel.

No one was injured in either incident.

- Jim

[gunnut69]

I don't understand.  The smaller diameter 9mm bullets should have been blown from the barrel.  While they are smaller the difference is small.  There should have been ample pressure developed to force the 9mm projectiles from the 40 caliber bore. More so since there seems to have been enough pressure generated by the 9mm round to cycle the action...  I wonder if there may have been something else in the bore that caused the obstruction.  If the 9mm ammo was using a cast, gas checked bullets I would bet on a gas check coming loose and blowing the weapon.  I wander also that a 9mm in a 40 cal would headspace well enough to be fired by the firing pin.  Would have the investigate further but I not heard of anything like this before but have heard of people making mistakes and then groping for an excuse.  In any case if the rounds functioned the weapon the bullet would not have lodged in the bore...

[John Traveler]

Check 9mm cartridge dimensions and the .40 chamber dimensions.  

Is it possible that the first chambered 9mm round formed a bore obstruction and the following round burst the barrel???

[JimInNJ]

I don’t really understand either.  I posted the story here kind of hoping for a reality check.

One would think that a 9mm bullet would be blown clear.  I think it is small enough not to be engraved by the rifling at all, so there shouldn’t be enough friction to hold it in the bore.  Do those carbines have any kind of muzzle break or flash hider that it could get wedged in?

I also have trouble understanding what would support the case for the firing pin to do its job.

My friend says he handled his department’s damaged weapon and saw pictures of the one from the neighboring township.  There are apparently convinced that their problem was caused by one box of 9mm ammo that was still in the locker from before they switched over to .40 S&W.

To me it sounds more like a case of a light handgun load with a heavy jacketed bullet not making it out of the carbine length barrel.

- Jim

[JimInNJ]

John,

That was my first idea.  Sort of like a 20ga shell in front of a 12ga.  But it didn't seem to me to fit with it bursting at the muzzle.

I am looking at a 9mm case and a .40 S&W case.  The one will drop into the other.  A 9mm bullet may not be big enough to engage the rifling in a .40, but an entire 9mm cartridge case looks might be just big enough.

Could it be that the first round disappeared into the breach and didn't fire, so they racked the action again pushing the first cartridge(s) up the bore until there was enough friction to hold one back against the bolt face tight enough to fire?  Ouch.

I have got to ask my friend what they found in the remains of that barrel.  Bullets or entire cartridges.

- Jim

[John Traveler]

One more thing...

I once saw some thin-jacketed 9mm bullets fired out of a snub-nosed S&W revolver and recovered in water-filled tank.

The bullets were horribly mushroomed, but NOT from impacting water!  It was the bullet bases that mushroomed, making us think that high chamber pressures caused the bullet distortion.

[KN]

I would agree with JimInNJ's theory. First round went part way up the bore and then they chambered another round. Ka-Boom!   KN