SGC 9mm - Catastorphic Failure - Almost lost an eye :(

[Hossballs]

Rather than join in on the witch hunt that seems to be going on toward SGC (BTW I've no interest or affiliation to SGC in any way) and make statements like ‘send it back for a full refund’ and ‘the rifle was not fit for purpose’ etc it is worth looking for a possible cause.

To blame the gun manufacturer for this ‘catastrophic failure’ is extraordinarily premature, indeed failures of this type that can be attributed to design, manufacture or materials are virtually unheard of. Such failures are almost without exception caused by overpressure ammunition and/or operational error.
Looking at the photographs it is clear, especially from the peeling around the charging handle and picatinny rail that this gun has been subject to a sudden and violent over pressure – certainly not as a result of gradual wear related fatigue.

A typical cause of such blow-ups is when the shooter experiences a miss-fire and works the charging handle to chamber a fresh round, instead of ejecting a ‘dud’ round the bolt pulls the case away from the bullet head and ejects the case and powder (if you are firing quickly it is easy to miss the incomplete round being ejected). As the heavy bolt picks up the next round it has sufficient inertia to ram a live round in behind the bullet head that is already lodged in the chamber throat/rifling lead of the barrel – at the same time the head of the fresh round is pushed back into the case compressing the powder charge. When that firing pin goes down you are literally detonating a small bomb.

The 9mm round is a bit like a helicopter – a bad idea that has been made to work regardless. One of the big problems with the 9mm is that when using lighter bullet weights such as 115gr, to maintain the rounds OAL lighter bullets sit well up in the case so that there is precious little brass gripping the bullet. As a result bullets are easily pulled out of or pushed into the case creating dangerous situations.

My advice to anyone with this class of firearm is to stick to heavier bullets, be diligent with the rounds OAL and dry rack a full mag through the gun to see whether any potential for the kind of separation of case and head exists as outlined above (only do this whilst safely pointing down range not in the spare room!).

Here’s a typical example of such a thing happening with a M16 – fortunately this shooter wasn’t injured either.
http://www.liveleak.com/view?i=ed3_1333816122

[the running man]

Good post,welcome to the forum, excellent theory on the probable cause of detonation,and the best I've heard yet,better than mine any way! I like the helicopter refrence! :goodjob:

[M99]

Good post,welcome to the forum, excellent theory on the probable cause of detonation,and the best I've heard yet,better than mine any way! I like the helicopter refrence! :goodjob:

I suggested a stuck round in the barrel on page 2!!

Which is why I had asked about factory or hand loads - as in one of the OPs other posts he had commented on his handloads being loose in the shell.

Mike

[the running man]

I know,but his sounded better!

[phaedra1106]

Just to clarify, I was shooting PPU factory ammo, there was def. not a bullet stuck in the barrel as I had only fired 15 shots in 2 groups, 10 on the top target face and 5 on the lower, I saw a hole appear after each shot was fired. I also checked the round was chambered fully before firing as mis-feeds have been a problem for several owners using both factory and reloaded ammo. There were no jams, mis-feeds, non-firing rounds or any other type of error while firing the first 15 rounds.

The charging handle was only used once to retract the bolt to its locked back position ready to be released and load the first round, after that it's a simple blow back system and the bolt is held back again after each shot until the release lever is pressed and it then goes forward loading the next round.

I have never suggested that it was due to gradual wear and tear, I've only had it a month and put less than 300rnds through it so that thought hadn't crossed my mind.

After the incident the barrel was empty and a 6th hole was present in the lower target so no blockage of the fired round. I've even pulled and checked half of my remaining PPU ammunition against some kindly supplied from another forum member and dimensions and powder weight etc. are identical.

[25Pdr]

Hossballs Quote.....
[The 9mm round is a bit like a helicopter – a bad idea that has been made to work regardless. One of the big problems with the 9mm is that when using lighter bullet weights such as 115gr, to maintain the rounds OAL lighter bullets sit well up in the case so that there is precious little brass gripping the bullet. As a result bullets are easily pulled out of or pushed into the case creating dangerous situations.]

That makes a lot of sense. Back in the pistol days, I witnessed a catastrophic failure of a Erfurt Luger.

The toggle had come back obviously faster than usual and sheared both ramps off the frame instead of riding up them.


The shooter was using 125Gr cast ahead of Noble No3 similar to Bullseye.The bullets were so loose you could move them in and out by hand.

Turns out the shooter,(new reloader) had used a Lee Loader kit, it obviously didn't resize the cases properly.

9mm runs at 35,000 PSI normally, don't know what a compressed load would be.

Lee Loader Kit.

[DanTheMan]

The sgc lr is a rifle,is it not,I would expect the metal on the walls of the reciver to be somewhat thicker than that of a pistol......therefore,I would honestly have to hazzard a guess,and this is a guess and only my personall opinion....that the lr should really be able to handle any hot 9mm round

Loads of Unicorn owners are getting through a mountain of 1200 rd tins of Hirtenberger L7A1 which is +p (SMG ammo) with no issues, it's very accurate out to 200yds and cycles perfectly.

The manual requests that only NATO/SAMMI or US mil spec ammo should be used to ensure the action cycles ok, as low powered reloads may not cycle properly, and lead bullets eventually block up the flash hiders on the early models but the later back bored barrels handle this better.

[meles meles]

The 9mm round is a bit like a helicopter – a bad idea that has been made to work regardless.

It's widely accepted amongst we navigators, though not all pilots, that helicopters don't actually fly: they are just so ugly that the earth repels them.

[kennyc]

The 9mm round is a bit like a helicopter – a bad idea that has been made to work regardless.

It's widely accepted amongst we navigators, though not all pilots, that helicopters don't actually fly: they are just so ugly that the earth repels them.

helicopters? 10,000 pieces flying in close formation

[Quarters]

Could this be an Out of Battery Discharge?

Google it with AR15 at the end.