New members must contact admin@mg42.us to have their account activated. Please include your username.

salt

MG blew up in my face! Need help

Anything MG42 related.
hakentt
Stabshauptmann
Stabshauptmann
Posts: 235
Joined: Mon May 08, 2006 11:52 pm
Location: Arizona

MG blew up in my face! Need help

Postby hakentt » Thu Apr 13, 2017 3:03 am

I bought all of the parts to get my M53 semi shooting 308. I also bought some new german 7.62 ammo. 3 rounds barely held the pressure and 4th one blew up, blew open the breech door and busted out extractor from the bolt, I felt the pressure against my face, good that I wear protection.
Now what is going on here? the barrel that I bought is from MG3 and there is a cut out, so there is nothing supporting the cartridge about 4mm to the end, need expert advice please.

https://s25.postimg.org/ipfk4gn8v/mg3ammoproblem.jpg

Also I decided to replace my rotten Yugo 8mm barrel with new Green Mountain chrome lined one. After 10 rounds , markings start appearing near the end of cartridge and I get fail to eject and primers become unstable. I have shot Yugo 8mm from my old barrel without issues. I compared and everything looks the same as my old Yugo barrel visually. So once the barrel heats up I get these problems, I wonder what is going on? Something going out of spec?

https://s25.postimg.org/u323fnxrj/green ... roblem.jpg

hakentt
Stabshauptmann
Stabshauptmann
Posts: 235
Joined: Mon May 08, 2006 11:52 pm
Location: Arizona

Re: MG blew up in my face! Need help

Postby hakentt » Thu Apr 13, 2017 3:25 pm

Image

Image

messerschmittfan
Stabshauptmann
Stabshauptmann
Posts: 161
Joined: Tue Apr 21, 2009 4:29 pm
Anti-spam: Mg42

Re: MG blew up in my face! Need help

Postby messerschmittfan » Thu Apr 13, 2017 3:33 pm

Why in the world is the end of the barrel chambered so deep? There is no way that the case can be supported by the bolt so you have the end of the cartridge hanging out there with no support. Take a look at the chamber at the end of your Yugo barrel to see what I mean. DO NOT SHOOT your gun with that barrel again or it will pop the case again this time causing you damage. Harry

User avatar
JBaum
Administrator
Administrator
Posts: 2798
Joined: Sat Mar 12, 2005 8:41 pm
Location: Lisbon, Ohio
Contact:

Re: MG blew up in my face! Need help

Postby JBaum » Thu Apr 13, 2017 7:14 pm

messerschmittfan is absolutely correct. With that much of the chamber missing, I'm surprised the first three shots didn't blow too. Looks like that barrel is scrap. Where did you get it?
John@German<remove this>Manuals.com

http://www.GermanManuals.com

hakentt
Stabshauptmann
Stabshauptmann
Posts: 235
Joined: Mon May 08, 2006 11:52 pm
Location: Arizona

Re: MG blew up in my face! Need help

Postby hakentt » Thu Apr 13, 2017 7:46 pm

jbaum wrote:messerschmittfan is absolutely correct. With that much of the chamber missing, I'm surprised the first three shots didn't blow too. Looks like that barrel is scrap. Where did you get it?


At the gun show. The cut seems to be factory, have you ever seen mg3 barrel like that? What is your opinion on my 8mm shells?

User avatar
Der Alder
Oberstleutnant
Oberstleutnant
Posts: 445
Joined: Sun Jan 14, 2007 7:27 am
Location: NW PA

Re: MG blew up in my face! Need help

Postby Der Alder » Thu Apr 13, 2017 7:49 pm

Here is a pic of one of my surplus MG3 barrels.

Image

User avatar
Der Alder
Oberstleutnant
Oberstleutnant
Posts: 445
Joined: Sun Jan 14, 2007 7:27 am
Location: NW PA

Re: MG blew up in my face! Need help

Postby Der Alder » Thu Apr 13, 2017 8:03 pm

My advise is to use surplus barrels and check them for head space.
Glad you are OK BTW.

hakentt
Stabshauptmann
Stabshauptmann
Posts: 235
Joined: Mon May 08, 2006 11:52 pm
Location: Arizona

Re: MG blew up in my face! Need help

Postby hakentt » Thu Apr 13, 2017 8:12 pm

Der Alder wrote:My advise is to use surplus barrels and check them for head space.
Glad you are OK BTW.


Also I got two recuperators, both Yugo and they don't compress flush, the plunger stops with about 5mm still to go.

User avatar
Der Alder
Oberstleutnant
Oberstleutnant
Posts: 445
Joined: Sun Jan 14, 2007 7:27 am
Location: NW PA

Re: MG blew up in my face! Need help

Postby Der Alder » Thu Apr 13, 2017 8:23 pm

hakentt wrote:
Der Alder wrote:My advise is to use surplus barrels and check them for head space.
Glad you are OK BTW.


Also I got two recuperators, both Yugo and they don't compress flush, the plunger stops with about 5mm still to go.



That sounds about right...recups of all types including the MG3, the head does not fully compress flush with the tube. The question on them always is if the spring rate is still in spec.

hakentt
Stabshauptmann
Stabshauptmann
Posts: 235
Joined: Mon May 08, 2006 11:52 pm
Location: Arizona

Re: MG blew up in my face! Need help

Postby hakentt » Thu Apr 13, 2017 9:17 pm

Der Alder wrote:That sounds about right...recups of all types including the MG3, the head does not fully compress flush with the tube. The question on them always is if the spring rate is still in spec.


According to the manual it should be flush and barrel should be stopped by the cam and not the recuperator.

viewtopic.php?t=5681

Or jbaum did not translate well from German.

by jbaum » Sun Jul 22, 2007 5:38 pm

"The Barrel strikes on the front side of the Unlocking Cams and is pushed again forward by the Recuperator."

That's a line from the MG3 manual that I've almost finished translating. It's on page 241/2, second paragraph from the ZDv 3/14 manual, which is available for free download in its original German on my website Links page ( http://www.GermanManuals.com/Links.html ). The English translation of this manual should be done in about a week.

User avatar
JBaum
Administrator
Administrator
Posts: 2798
Joined: Sat Mar 12, 2005 8:41 pm
Location: Lisbon, Ohio
Contact:

Re: MG blew up in my face! Need help

Postby JBaum » Thu Apr 13, 2017 9:28 pm

hakentt wrote:
jbaum wrote:messerschmittfan is absolutely correct. With that much of the chamber missing, I'm surprised the first three shots didn't blow too. Looks like that barrel is scrap. Where did you get it?


At the gun show. The cut seems to be factory, have you ever seen mg3 barrel like that? What is your opinion on my 8mm shells?


No, I never saw any barrel with the chamber drilled like that. 8mm shells look near ready to blow. Did you check headspace?
John@German<remove this>Manuals.com

http://www.GermanManuals.com

hakentt
Stabshauptmann
Stabshauptmann
Posts: 235
Joined: Mon May 08, 2006 11:52 pm
Location: Arizona

Re: MG blew up in my face! Need help

Postby hakentt » Thu Apr 13, 2017 11:40 pm

jbaum wrote: 8mm shells look near ready to blow. Did you check headspace?


I checked it face of the bolt to the barrel has 0.5mm clearance with rollers fully locked, the same as my old yugo. If headspace was bad then it would show on first 10 rounds? Do you have automotive feeler gauges? Can you take your best barrel bolt heat and jam it together and give me a reading?

Sw1ngK1ng
Oberstabsgefreiter
Oberstabsgefreiter
Posts: 31
Joined: Wed Dec 21, 2016 4:58 pm
Anti-spam: Mg42
Location: Virginia

Re: MG blew up in my face! Need help

Postby Sw1ngK1ng » Thu Apr 13, 2017 11:52 pm

hakentt wrote:
jbaum wrote: 8mm shells look near ready to blow. Did you check headspace?


I checked it face of the bolt to the barrel has 0.5mm clearance with rollers fully locked, the same as my old yugo. If headspace was bad then it would show on first 10 rounds? Do you have automotive feeler gauges? Can you take your best barrel bolt heat and jam it together and give me a reading?


I don't think head spacing is your issue here, it just looks like it is ridiculously countersunk. The countersink won't effect where the shoulder in the chamber sits in relation to the bolt face. Your simply missing the back of the chamber but the depth of the chamber is likely correct, not that it would even matter if it isn't at this point.

User avatar
Der Alder
Oberstleutnant
Oberstleutnant
Posts: 445
Joined: Sun Jan 14, 2007 7:27 am
Location: NW PA

Re: MG blew up in my face! Need help

Postby Der Alder » Fri Apr 14, 2017 10:03 am

hakentt wrote:
Der Alder wrote:That sounds about right...recups of all types including the MG3, the head does not fully compress flush with the tube. The question on them always is if the spring rate is still in spec.


According to the manual it should be flush and barrel should be stopped by the cam and not the recuperator.

viewtopic.php?t=5681


by jbaum » Sun Jul 22, 2007 5:38 pm

"The Barrel strikes on the front side of the Unlocking Cams and is pushed again forward by the Recuperator."

That's a line from the MG3 manual that I've almost finished translating. It's on page 241/2, second paragraph from the ZDv 3/14 manual, which is available for free download in its original German on my website Links page ( http://www.GermanManuals.com/Links.html ). The English translation of this manual should be done in about a week.


I was talking about the recuperator's head vs recuperator tube, (the recup itself) not the barrel and its relation to the recuperator.

User avatar
Der Alder
Oberstleutnant
Oberstleutnant
Posts: 445
Joined: Sun Jan 14, 2007 7:27 am
Location: NW PA

Re: MG blew up in my face! Need help

Postby Der Alder » Fri Apr 14, 2017 10:12 am

Sw1ngK1ng wrote:
hakentt wrote:
jbaum wrote: 8mm shells look near ready to blow. Did you check headspace?


I checked it face of the bolt to the barrel has 0.5mm clearance with rollers fully locked, the same as my old yugo. If headspace was bad then it would show on first 10 rounds? Do you have automotive feeler gauges? Can you take your best barrel bolt heat and jam it together and give me a reading?


I don't think head spacing is your issue here, it just looks like it is ridiculously countersunk. The countersink won't effect where the shoulder in the chamber sits in relation to the bolt face. Your simply missing the back of the chamber but the depth of the chamber is likely correct, not that it would even matter if it isn't at this point.


He had a question too about the 8mm barrel and that sounds like a HS issue, which is why we mentioned that...the .308 countersunk barrel is simply junk and way out of spec.

hakentt
Stabshauptmann
Stabshauptmann
Posts: 235
Joined: Mon May 08, 2006 11:52 pm
Location: Arizona

Re: MG blew up in my face! Need help

Postby hakentt » Fri Apr 14, 2017 1:55 pm

Der Alder wrote:I was talking about the recuperator's head vs recuperator tube, (the recup itself) not the barrel and its relation to the recuperator.


I was talking about recup head vs recup tube. Booth of mine do compress to the end, it will appear that it stops about 5mm to the end but if I put my whole weight behind it, it will compress. Do you know why is the MG3 barrel counter sunk like that, is it for blank ammo only?

When you say 8mm barrel has HS issue, then is it too tight or too lose?

messerschmittfan
Stabshauptmann
Stabshauptmann
Posts: 161
Joined: Tue Apr 21, 2009 4:29 pm
Anti-spam: Mg42

Re: MG blew up in my face! Need help

Postby messerschmittfan » Fri Apr 14, 2017 2:51 pm

I looked at all five of my MG42's and one M53 barrels. I have one Austrian 7.62x51 NATO conversion units along with six spare barrels in 7.92x57 mm WWII German barrels and two Israeli 7.92x57 mm chrome lined barrels and NONE of them have the barrel so deeply countersunk. I do not think there is a problem with headspace as the cartridge would be supported by it's neck and could be fired. I really think that that barrel was counter sunk at least twice what it should have been. DO NOT SHOOT anything out of it. Just my thoughts Harry

hakentt
Stabshauptmann
Stabshauptmann
Posts: 235
Joined: Mon May 08, 2006 11:52 pm
Location: Arizona

Re: MG blew up in my face! Need help

Postby hakentt » Fri Apr 14, 2017 4:08 pm

On my 8mm green mountain barrel, checking headspace visually. I removed the extractor and with bolt facing down on the barrel I get no visual clearance with rollers fully locked up, when I turn the barrel around now bolt hangs down there is a 0.5mm gap and I can see the light, rollers are still locked, so the only slack is in the cam and rollers. Can anybody do the same test on their good known combination and tell me if you get the same result.
headspacemg53.jpg

User avatar
JBaum
Administrator
Administrator
Posts: 2798
Joined: Sat Mar 12, 2005 8:41 pm
Location: Lisbon, Ohio
Contact:

Re: MG blew up in my face! Need help

Postby JBaum » Fri Apr 14, 2017 9:46 pm

Headspace is not measured by the gap between the bolt face and chamber face. That measurement is only indirectly related to headspace. I wrote a detailed explanation of properly checking headspace on the 42 on here years ago. Do a search.
John@German<remove this>Manuals.com

http://www.GermanManuals.com

hakentt
Stabshauptmann
Stabshauptmann
Posts: 235
Joined: Mon May 08, 2006 11:52 pm
Location: Arizona

Re: MG blew up in my face! Need help

Postby hakentt » Fri Apr 14, 2017 10:36 pm

jbaum wrote: I wrote a detailed explanation of properly checking headspace on the 42 on here years ago. Do a search.


Can't find anything about headspace, bunch of worthless threads come up. Can you please do the same check I did and report here?


Return to “MG42 General Discussion”



Who is online

Users browsing this forum: No registered users and 2 guests

cron