Kaboom :-\ . 223 pics and video

[Larry Gibson]

That's why flatness of a fired primer is a poor indication of pressure. I tested some Winchester white box M193 a few years back for a friend. He said he was getting 3340 fps from his 20" AR. That is a bit fast.

I stopped after 7 rounds as rounds 5 and 6 hit 68,300 psi. Average for the 7 rounds was 65,700 psi. Velocity was 3351 fps out of the 21" test barrel. That is a bit warm. Point is by the look of the primers, expasion ring and case head expansion measurements there was no indication of that much psi.

I have pressure tested thousand of rounds over the last 8 years and seldom consider condition of a fired primer anymore.

[MaryB]

To many different primers and different hardness of them...

[higgins]

A Lee Factory Crimp Die will allow you to get a good crimp without the occasional case buckling seen when applying a firm roll crimp on a case that is a tad longer then the one used to adjust the die.

[cpaspr]

I do believe the talk about 24gr of H335 behind 110 grains of projectiles is a red herring. I don't care if the stuck in the bore item is 10gr or 55gr, once you fire the new bullet into anything that is lodged in a barrel as tight as that first 55gr projectile, you're going to have a blown up rifle.

PH - I don't think the second bullet fired into the bullet stuck in the bore. The bullet of the second round ran into the bullet stuck in the bore, pushing the second bullet back in the case. So now both bullets were nose to tail, ahead of the powder. One bullet was partially in the case, the other was tight against it's nose. So when the trigger was pulled, it really was the same as if there was a single 110gr bullet ahead of the powder.

[Larry Gibson]

Concur with cpaspr ^^^^^^

[PbHurler]

Nothing to add other than I'm glad you weren't hurt. You'll acquire a new rifle: harder to do with body parts.

[Prospector Howard]

PH - I don't think the second bullet fired into the bullet stuck in the bore. The bullet of the second round ran into the bullet stuck in the bore, pushing the second bullet back in the case. So now both bullets were nose to tail, ahead of the powder. One bullet was partially in the case, the other was tight against it's nose. So when the trigger was pulled, it really was the same as if there was a single 110gr bullet ahead of the powder.

I don't want to beat this into the ground, but I think most people underestimate the energy in a primer. I've never purposely or accidently fired a "primer only" squib in any firearm including a 55gr jacketed bullet in a .223/5.56, but I'd bet the bullet went into the barrell more than you're thinking in your theory. Either way you have a stuck bullet as Larry said and a bullet behind it that isn't stuck. That's really not the same as one 110gr bullet. I don't think the distance between them matters as much as you all do. Also, I don't think I want to ruin any rifles to test these theories to prove anything.

[popper]

OOB thought was incorrect - looking closely at the case head - what is left of it. Totally extruded into the bolt face. Bolt had to be locked up. I'd be surprised if it unlocked by gas pressure at all.
edit: yes the primer was dented. No there is no spring like an AK. You can test the 'interlock' of the bolt by rotating and pushing on the FP base. Mine move when bolt is ~1/2 way locked. Same as the AR15 (BO). Bolt rotates when it hits the case head but I don't think the hammer can fall until near lockup.

[M-Tecs]

The hammer will fall anytime the carrier is out of the way. The firing pin should not protrude from the bolt face until the bolt is rotated into battery.

To test with carrier out and the bolt all the way forward hold the firing pin all the way in and push the bolt in and not when the pin protrudes from the bolt face.

[adam_mac84]

Thanks for the great discussion guys (am the OP). I have since changed my reloading practices, and will never clear a malfunction without a second look at what is coming out (even on the clock). Saving a few cents per round in 223 cost me $700 in replacement firearm, so although I am very thankful to not have been injured, was a relatively $$ lesson to learn (but no cost compares to a permanent physical injury!!).

I still have a hard time on a primer only squib (wouldn't there have been a 'pop' or 'puff' sound?), but the evidence is hard to refute. My OAL shouldn't have put the bullet into the lands causing it to get 'grabbed' if it were just a dead strike. I have gone frame by frame in the video (100 fps). I did not catch a good image of the casing ejected, can only see it. If I really zoom in, I PERSONALLY believe I see a taper on the end of the case. Leaving bullet in the barrel. the 110grains did get pushed out, but not before destruction of the upper. I do think that bullet set back was a main part of this event. Either due to obstruction, or chambering process.

To me, I will assume and operate from this point as the entire thing was my fault (reloading practice faults and malfunction clearing faults). By fixing these I hope to reduce my chances of future failure/injury.

[Larry Gibson]

Excellent attitude.....learn from our own mistakes.......

Hold hard, shoot straight.....

[jonp]

With a bullet stuck in the throat, leade, etc. an AR bolt/carrier when drawn to the rear and released has sufficient momentum to push the next feeding bullet back into the case. I saw this many times over the years even with M193 and M855 ammo. It is particularly noticeable in FTE (failure to extract) where the fired case stays in the chamber, the action functions and the bullet of the feeding round is stopped by the case in the chamber. That bullet invariably gets pushed back into the case. In those instances the round will not chamber of course.

However, in the OPs case the soft jacketed bullet stuck in the leade was probably push a bit further into the bore while the bullet in the feeding cartridge was shoved back into the case. That in essence created a "110 gr bullet" (the combined weight of the 2 bullets) over 24 gr H335......obviously not good!

BTW; 24 gr H335 under a 55 gr bullet is a medium range 223 Rem load. It takes 25 - 25.5 gr to make the SAAMI MAP. It takes 26.5 to 27 gr to equal the 5.56 MAP. My standard load since the mid '70s has been 26.5 gr H335 in LC cases with a WSR or CCI 450 primer under a 55 gr Hornady SX (12 and 14" twist barrels). The measured psi (Oehler M43) in a 223 Rem chamber runs right at 59,500 to 60,000 psi.

Note; the psi I give are transducer/gauge psi's. The previous post psi's are CUPs. I'll also add that M193 made since around 2003 or 4 has the same measured psi as M855; 60 to 62,000 + psi. The older M193 ran around 58,000 psi which is about 4,000 +/- psi more than most 223 Rem factory cartridges are loaded to.

Insufficient crimp on the second or would it matter as the force of chambering would push the bullet back no matter what?