As I recently mentioned in another thread, I picked up a preban M17s yesterday.  Just to have something a bit different, yet still be able to legally have the flash hider installed.  I decided to shoot a 30 round mag through it this afternoon just to see if it would run.  Bad idea.  

I turned on the red dot that came with the rifle, shouldered it, and slowly fired off 10 rounds.  The noxious gases from the chamber were bad.  I looked the rifle over as I got a lung full of fresh air.  I reshouldered the rifle and commenced to fire 10 more rounds. Once again, the gases coming from this thing were horrific.  Nothing visible, just chokingly strong.  I decided to finish off the final 10 rounds with the butt of the bullpup tucked up under my shoulder so I wouldn't have to endure the fumes.  I swear it was that bad.  Thank God I didn't have it shouldered when this happened.  

On the 22nd overall round, the pup made a very unusual "sproing" noise.  Along with the noise, I felt my ribcage area burning like fire.  It took me a few seconds to realize what had just happened.  It had blown the floorplate off the OKay USGI mag, the upper was separated from the lower, and a wadded up case was stuck in the upper receiver. Not in the chamber. The barrel was clear.  Upon further review, a large hunk of metal from the inside of the upper receiver was peeled back along one of the internal rails that the bolt carrier slides in. The bolt/carrier was not damaged.

The only thing I can think of is that the push pins had walked out.  Still though, the bolt carrier slides entirely within the upper.  Just because the hammer and mag (within the lower receiver) had dropped away, you wouldn't think it would cause this much turmoil in the chamber area.  

[blue]Any thoughts on another cause of this malfunction?[/blue]

This what the rifle looked like after the malfunction.
[img]http://www.hunting-pictures.com/members/Cope/Blowout.jpg[/img]

My Shirt.
[img]http://www.hunting-pictures.com/members/Cope/shirt50jpg[/img]

The wadded up round of South African.
[img]http://www.hunting-pictures.com/members/Cope/round1.jpg[/img]

The inside of the reciever.
[img]http://www.hunting-pictures.com/members/Cope/Receiver1.jpg[/img]

 
Thanks




spelling

Cope- sorry to hear about that.  I have a preban M17s that used to separate the upper and lower receivers.  The receiver tongs that held the pin would separate and loosen as I shot. The rifle began to double and triple.  I sent it back and they gave me the new receiver design that can't come apart.  

I have no idea about what caused your problem though. Very curious.

Call Jarod over there and tell him what happened.  He will send you a shipping label and they will take care of it.  Good luck.

First of all,

Put your hands together and thank the Lord you were not seriously injured.



Looks to me from the photos that the case ruptured when outside of the chamber, perhaps that is what scraped the metal on the inside of the reciever.  These are my guesses:

Maybe the firing pin stuck and "slam fired" the round, which fired before fully entering the chamber, thus accounting for the floorplate poping off and the reciever damage.  Check the bolt carrier and firing pin, as well as the springs, for any wear, damage, obstructions, etc.

OR

The recoil spring jammed up, got caught somehow, etc.(ie: the sound you heard) and the lack of forward pressure on the bolt caused it to open prematurely.  The cartridge exited the chamber before the bullet, thus the case was subjected to the full pressure that existed in the barrel.  The result is that the partially unsupported case ruptured, which could also blow off the mag floorplate.


I don't claim to be an expert, but I hope this helps you out.  PLEASE be VERY careful when shooting this and you probably should have this checked out by a Bushmaster armorer/gunsmith, or at least someone who is very familiar with that type of action.

Just my .02,

Urban
[sniper]  

First of all,

Put your hands together and thank the Lord you were not seriously injured.



Looks to me from the photos that the case ruptured when outside of the chamber, perhaps that is what scraped the metal on the inside of the reciever.  These are my guesses:

Maybe the firing pin stuck and "slam fired" the round, which fired before fully entering the chamber, thus accounting for the floorplate poping off and the reciever damage.  Check the bolt carrier and firing pin, as well as the springs, for any wear, damage, obstructions, etc.

OR

The recoil spring jammed up, got caught somehow, etc.(ie: the sound you heard) and the lack of forward pressure on the bolt caused it to open prematurely.  The cartridge exited the chamber before the bullet, thus the case was subjected to the full pressure that existed in the barrel.  The result is that the partially unsupported case ruptured, which could also blow off the mag floorplate.


I don't claim to be an expert, but I hope this helps you out.  PLEASE be VERY careful when shooting this and you probably should have this checked out by a Bushmaster armorer/gunsmith, or at least someone who is very familiar with that type of action.

Just my .02,

Urban
[sniper]  

Ratters,

Now that you mention it, I DID get a double in the second round of 10 shots.

I had written BM a couple weeks ago, when I was debating on buying this thing.  I wanted to verify the preban status, as well as any costs for the upgrades.  They did verify it as preban, but said it would cost me $100 to have the upgrades done.  

I have read second hand that BM didn't recall the early M17's, but did offer free upgrades if people were experiencing problems.  I guess I'll find out shortly whether they will charge me the hundred bucks or not.  I imagine this would qualify as a problem. The big red strawberry on my right nipple sure seems to think so.[BD]  

Thanks for the response.    

Hey,

Just took another look at the pics and saw one of the recoil springs looks like it poped off of the rear plate on the bolt assembly.  Maybe this uneven-ness caused the bolt to yaw to one side, and in the process, cut away on the inside of the reciever.

Bottom line: check the WHOLE gun, but REALLY look at the bolt/carrier/spring assembly.

another .02

Urban

Damn, it looks like a part of the case is on the rail.  Talk about major problem.

Urban,

I just noticed that one of the retaining rings that holds each spring rod in placed has jumped out of it's groove.  This is located in front of the carrier.  With this ring not being seated, it allows one spring to push the recoil plate at the rear out of kilter.  Good eyes.  Just noticed that one myself. I was looking for chunks of missing metal, rather than a retaining ring out of place.

This thing is useless at this point.  So don't worry about me shooting it any more in this condition. I will be contacting BM tomorrow to see what it is going to take to get this cured.

Thanks for the feedback.    

They did mine for free but that was about five years ago.  Put this on the Bushmaster forum over on the Industry Forums section.  Jarod is usually very helpful when he sees a problem.  It is still well worth the hundred bucks though.  

No, that's actually the rail itself rolled up.

No, the guy I got it from seems to be an honest guy.  He tells me that he took it in on trade and never shot it.  He has another one.  I trust the guy.  And yes, it's DEFINITELY time for the upgrade at this point.

damn man your right those pics are uncool just glad to hear u and no one else was hurt execpt for your pride maybe

Pride hell, that was one of my favorite T shirts! [:(]

Is that a PREBAN mag?!!?!

Happy for you that you are here to "post".
I'll look for the post-ban model now...

Really, glad you're able to tell us the story and I think Bushmaster will accomodate you.
Wow.

I hope Bushmaster stands by its product and repairs or replaces your rifle.

I was just checking their site, and noticed they have a 2 year parts and labor warranty on the new models.  I'm not looking for a freebee, and was actually planning on sending it back before this happened.  I guess their decision will determine whether or not I want to buy any more of their products.  No biggy.  Just happy to be here. literally.  

Thanks for the concern.

BM says it was faulty ammo, and they would do the upgrades for $100.  LOL

Faulty ammo makes a weapon fire out of battery?

Yep,

They stood behind it for $115.  I'm sure it cost them at least that much to do the upgrade, along with the ATF Paperwork.

Now that it is in factory new condition, I just wish someone would buy this thing!

[url]http://www.ar15.com/forums/topic.html?id=50486[/url]

Anyone wanna trade a 700LTR with base and rings for the preban?



 

The only thing I have on the block is a stainless mini 14 preban w/Butler creek folder, optics base, and mgw 90 rd drum.  Doubt you are interested, but I thought I'd post.