Went off to the range with a friend today who has never shot before in his life.  Took a can of '92 RORG, 300rnd of 200gr Fiocchi .45, the M&P 15, the XD45, and the S&W 1911.

We decided to fire the M&P 15 first, easier to handle a benched rifle @25yd than a .45 for a first timer.  I sat down with a 20-rounder after giving a dry-fire demonstration to make sure everything was setup right and at about five rounds in I hear a different kind of 'boom' and something smells.  Picked my head up and what's this?  The magazine spring is sticking out the bottom of the magazine?  Uh-oh.

Turns out the round didn't fully chamber but was close enough that the thing fired.  The round exited the barrel and went downrange, and the rest of the force went into the receiver and blew out the bottom of the magazine.

No damage to the bore, chamber, or receivers thankfully.  The bolt got mangled pretty good and was a pain in the neck to get loose (with the blown round still attached) but I got it out eventually.

After all this I went home, picked up the Bushy Carbon-15, swapped bolts, and fired off 20 more without a hitch at the indoor range.  Looks like all I'm out is a bolt/extractor and a magazine base plate and spring.  Could've been a lot worse.

Images are clicky for full-size versions.

I'd be checking the barrel extension REALLY carefully before you fire it anymore.  Likely cracked.  Had a similar incident earlier in the year and there was a lot of somewhat hidden damage that didn't really show up until a thorough inspection and cleaning.

What ammo was it?  And did you build the gun yourself?  The ammo manufacturer will likely cover the damages if you keep all the box info and the incident round.

But glad you're okay!

I doubt that the bolt was out of battery.    Specifically, check your brass and see if you can see the swagged material in the case head that comes from the ejector as the bolt rotates during unlocking(like that shown on the head of my brass below).    This will signify more than anything to what degree the bolt was locked into battery.

I'm betting that the bolt had full lug engagement with the lugs of the barrel extension.


Maybe poorly set up headspace or way the barrel extension was installed to the barrel allowing for a bit more unsupported area of the case head(maybe).

But I'd be more suspect that it's ammo related.


Why?   I've had my own run ins with Radway Green in a rifle that otherwise has been just fine with all variety of ammo from Wolf 223, Q3131A/XM193, and a wide variety of handloads.


Brass shouldn't come out looking like a damned belted mag.   I was on the ragged edge of having a kB with this shit, it was within 5 rounds of testing out a bandoleer of Radway Green 89.   I put aside what remained of what I had and it is sitting on the reloading bench in the garage to pull it down and look for something that might indicate why it did what it did.







I'll never touch Radway Green again.

Quoted: I'd be checking the barrel extension REALLY carefully before you fire it anymore.  Likely cracked.  Had a similar incident earlier in the year and there was a lot of somewhat hidden damage that didn't really show up until a thorough inspection and cleaning. What ammo was it?  And did you build the gun yourself?  The ammo manufacturer will likely cover the damages if you keep all the box info and the incident round. But glad you're okay!

Well it went through the 20 rounds of low-power (under 2000fps, frangible) fine after replacing the bolt, but it will get a good teardown, cleaning, and inspection tomorrow.

The ammo was Radway Green '92, and this is no build -- It's a Smith & Wesson M&P 15 with about 1200 rounds through it so far, cleaned every ~200.  I've only had it about a month, bought NIB.

I can't be sure where I got the ammo.. I got a few cans locally and a few from AIM.  Maybe S&W will be cool and replace the bolt and mag, but as long as there is no other damage I won't press the issue with them too much.

Originally Posted By uglygun I doubt that the bolt was out of battery. Specifically, check your brass and see if you can see the swagged material in the case head that comes from the ejector as the bolt rotates during unlocking(like that shown on the head of my brass below). This will signify more than anything to what degree the bolt was locked into battery. I'm betting that the bolt had full lug engagement with the lugs of the barrel extension. Maybe poorly set up headspace or way the barrel extension was installed to the barrel allowing for a bit more unsupported area of the case head(maybe). But I'd be more suspect that it's ammo related.

I think it's definitely a headspace issue of some kind, it's obvious that there was a good 2mm or so of unsupported brass at the head end, it expanded pretty well all the way around as you can see in the "big" picture if you click it.

I've only fired three different kinds of ammo from this thing, and I have never seen any evidence of bulging on any of the spent casings.

When I tried to clear it after this incident and was pushing and pulling the charging handle and forward assist, the bolt would not lock up, so I really doubt it was locked up when it happened.

Quoted: When I tried to clear it after this incident and was pushing and pulling the charging handle and forward assist, the bolt would not lock up, so I really doubt it was locked up when it happened.

It likely wouldn't lock up after the incident because the overall length of the case is probably much longer than that of an unfired case(or even that of a round that fails to extract).


Get out a set of calipers and check the overall length of that case, also do a check from head to the shoulder, and compare to the accepted specs for a properly sized round.

I'm betting the shoulder blew forward a few thousandths so it's no wonder why the bolt wouldn't lock back into battery.    At the very least the way the case head expanded is probably enough to cause problems with the tolerances the bolt needs to lock into battery.


The part of me that really would like to know what is going on with the barrel/bolt would be to send it to somebody who'd give an unbaised opinion after tearing it down, somebody who's actually cut AR15 barrels and installed barrel extensions after properly head spacing them.

Maybe it's just me, but that headstamp in the pic looks like 89 to me.  Isn't that supposed to be the underpowered stuff too?

Quoted: Maybe it's just me, but that headstamp in the pic looks like 89 to me.  Isn't that supposed to be the underpowered stuff too?

It's 92.  I could get a better picture, but I can see it here just fine.  The 2 is under the black stuff, there's no 8. ;)

ETA: In uglyguns it is 89 as he said.  Mine is 92.  

Quoted: Maybe it's just me, but that headstamp in the pic looks like 89 to me.  Isn't that supposed to be the underpowered stuff too?

In my picture, yes it is 89.


I'm fairly face shy about the whole concept of having RORG in my stash.    Maybe if I'm not doing anything tomorrow I'll finally pull down the remainder of what I have to see if I find any remarkably high or low charges.    

I've been shooting RORG '92 out of my DPMS. Out of ~200 rounds I've had 5-8 primers fall out. It fires, the round ejects, and it loads the next. However, that primer sticks in the chamber and wont let the bolt fully close. I'm really considering what to do with the 800 or so rounds I have left. Yeah, Radway is cheaper, but is it worth my and others' saftey?

Quoted: I've been shooting RORG '92 out of my DPMS. Out of ~200 rounds I've had 5-8 primers fall out. It fires, the round ejects, and it loads the next. However, that primer sticks in the chamber and wont let the bolt fully close. I'm really considering what to do with the 800 or so rounds I have left. Yeah, Radway is cheaper, but is it worth my and others' saftey?

That is something I hadn't even thought of.. what are you saying, the primer came out and stuck to the bolt face or something before it chambered the next round?

height=8

Quoted: height=8 Quoted: I've been shooting RORG '92 out of my DPMS. Out of ~200 rounds I've had 5-8 primers fall out. It fires, the round ejects, and it loads the next. However, that primer sticks in the chamber and wont let the bolt fully close. I'm really considering what to do with the 800 or so rounds I have left. Yeah, Radway is cheaper, but is it worth my and others' saftey? That is something I hadn't even thought of.. what are you saying, the primer came out and stuck to the bolt face or something before it chambered the next round?

Something like that. I noticed the bolt wasn't fully closing when I was firing, so quit shooting it. Upon cleaning the rifle, I found a primer smashed/stuck in the ribbing of the chamber. (I don't know the exact terminology.)

Those are the least horrific 'horrific pictures' I've ever seen.  Glad your alright, though, and I hope your blaster is, too.  

SB

Quoted: ETA: In uglyguns it is 89 as he said.  Mine is 92.

Whoops, my bad .  Too many pics

Had something similar to that happen to me at the range a few trips ago. Blew out the floorplate of the mag, but no damage to the gun anywhere that i've been able to find.

This was a bushy m4gery that has seen lots, and lots, and lots of use.

Very odd about the Radway; I have a batch of '91 that I put through the chronograph.  It was dead on for velocity compared to some Lake City 62 gr, and showed much lower SD and extreme spread than the Lake City, or anything else I tested that day.
No problems whatsoever, tho' I've only fired a couple hundred rounds of it.
Moon

STRANGE