The Firing Line Forums

Go Back   The Firing Line Forums > The Skunkworks > The Smithy

Reply
 
Thread Tools
Old November 5, 2012, 06:32 AM   #1
alex0535
Senior Member
 
Join Date: November 4, 2012
Location: Georgia
Posts: 781
Cartridges stuck in chamber after firing

Rifle is a Browning A-Bolt II chambered in 7mm mag.

First shell ejected without problems. The 2nd shot is where we ran into a problem. The bolt handle came up but would not slide back. We tried to diagnose the problem for a bit and decided to take it home.

I put the butt of the stock on the floor, lifted the bolt handle and hit it with my palm and the shell kicked out.

The next logical step was looking at the cartridge for any irregularities. There is a thin line that is not on unfired brass. The rest of it is clean.


The gun cycles unfired rounds smoothly through the action. The rounds we were shooting were decent quality but of unknown age. I have some newly purchased ammo for it.

Debating going out and shooting it today, trying the fresh ammo. The gun has been cleaned more thoughly, with more attention paid to cleaning the chamber than it has probably seen through most of its 17 years of existence. I am hoping that it was just needed to be cleaned, but any helpful imput is welcomed.
alex0535 is offline  
Old November 5, 2012, 08:22 AM   #2
jaguarxk120
Senior Member
 
Join Date: February 28, 2008
Location: Michigan
Posts: 1,995
You did not say if the fired rounds were factory or reloads.

If they were reloads, the thin line at the base of the case indicates stretching of the brass. In other words the shoulder was bumped too far back when reloaded.

Factory loadings should not do that.
jaguarxk120 is offline  
Old November 5, 2012, 08:29 AM   #3
Brian Pfleuger
Staff
 
Join Date: June 25, 2008
Location: Central, Southern NY, USA
Posts: 18,791
You describe the classic indications of a severe over-pressure rounds and incipient case head separation.

The 7mm Mag is a belted case and should, in theory, be head spacing on the belt, so shoulder position shouldn't affect much. I don't know much about the belted mags but I think I've read that many of them DON'T actually head space on belt. If that were true, shoulder position would matter. Someone else can help you there.

The first part is certainly classic pressure/head separation though.

Unknown rounds of unknown age could be carrying deteriorating powder that will not burn predictably. If they are reloads, the powder could be perfectly normal but a severe overcharge. Either way, don't shoot them anymore and stick to known (your own) reloads or factory ammo.
Brian Pfleuger is offline  
Old November 5, 2012, 06:20 PM   #4
alex0535
Senior Member
 
Join Date: November 4, 2012
Location: Georgia
Posts: 781
Rounds are factory loaded Winchester Supreme 150gr Power Point Plus. If there is a way to look up lot numbers for when these rounds are produced, let me know. The cartridges are nickle brass.

I didn't get out to shoot the new rounds today.
alex0535 is offline  
Old November 5, 2012, 06:58 PM   #5
James K
Staff
 
Join Date: March 17, 1999
Posts: 20,001
If a belted case does not headspace properly on the belt, there is something seriously wrong with the rifle or the cartridge. That is what the belt is there for (not, as some think, to strengthen the case head), to provide a case suppport (headspace) point for cartridges with insufficient shoulder to use for support, while allowing better feeding than a rim. (In other words, the belt acts like a small rim.)

But a bright line in that position on the case does indicate excessive headspace. There should be no problem in firing a few more rounds and seeing if other ammo has the same problem.

Jim
__________________
Jim K
James K is offline  
Old November 6, 2012, 04:14 PM   #6
loademwell
Senior Member
 
Join Date: November 6, 2012
Posts: 144
Been there! Did you shoot a bunch of those loads? Is so, and it happened one time, I would say it was a bad round.
If it happens more then once! Bad gun.

Are you a handloader? If so, make some light loads and check those casings to see if they are getting swelled belts or any imperfection for that matter. If so, again; BAD GUN

I have heard of this happening a few times with people that reload and use a collet die.
loademwell is offline  
Old November 6, 2012, 10:12 PM   #7
James K
Staff
 
Join Date: March 17, 1999
Posts: 20,001
Reloading for a belted magnum is still expensive because the front of the belt is a sharp angle with the case body and is a real stress riser. Cases often crack at that point after only a few firings because it is in the thinner part of the case, unlike a rim which is well behind the thickest part of the case.

The original reason for the belt was to provide case support (headspace) for cartridges like the .375 H&H Magnum. That cartridge was designed to be rimless, but it has almost no shoulder. Without a rim or a shoulder could easily be driven too far into the chamber even with a manually operated bolt action, and also could cushion the firing pin blow for lack of case support. So the belt was a compromise to get the feeding of a rimless case and almost the support of a rimmed case.

The problem came about when folks assumed that the belt was to strengthen the case head and began to equate a belted cartridge with power. So cartridge designers put belts on cartridges for pure hype, thus (inadvertently?) making sure shooters would have to buy a lot of nice new cartridges or at least brass if they wanted to shoot very much.

Jim
__________________
Jim K
James K is offline  
Old November 7, 2012, 08:52 AM   #8
jmr40
Senior Member
 
Join Date: June 15, 2008
Location: Georgia
Posts: 6,176
There was a recall on some Winchester 7mm rem mag ammo a few years ago because of over pressure ammo. It is possible some of this ammo is still on dealers shelves. I'd try another type of ammo.

The belt on most magnum chamberings is mainly just for decoration as James K points out. It should headspace just like any other non belted case. It does add another factor that can cause issues for reloaders to have to work around.
jmr40 is offline  
Old November 7, 2012, 09:25 AM   #9
alex0535
Senior Member
 
Join Date: November 4, 2012
Location: Georgia
Posts: 781
^The ammo came with the gun. My father got it from an old uncle of his.

With The gun having been born in 1995. Ammo is from some time after that. Gun seems in pretty good shape. Looks like it was taken into the woods a good bit, minor cosmetic stuff. But I doubt the old guy it came from was exactly running through boxes of ammo.

Box is mostly empty. He probably bought the ammo when he got it. Sighted in the rifle, took it hunting a few times and decided it was too much gun for this state and his age. I do not know if he purchased it used or not. Wish there were some way to figure out when it was from.
alex0535 is offline  
Old November 7, 2012, 06:01 PM   #10
hooligan1
Senior Member
 
Join Date: July 18, 2010
Location: Independence Missouri
Posts: 3,451
Try some Hornady 139 grn BTSP's through it, if it does the very same thing, take it to the Smith.
Use whatever commercial stuff you like, I found these to be somewhat light recoiling and very accurate, and they do nicely on whitetails.
__________________
Thanks for coming!
hooligan1 is offline  
Old November 7, 2012, 08:57 PM   #11
603Country
Senior Member
 
Join Date: January 6, 2011
Location: Thornton, Texas
Posts: 2,371
If the problem is the rifle chamber, and that if headspacing on the belt is causing too much case stretch, you can (if you reload) partial resize so that the cases would then headspace on the shoulder. We did that for my son-in-law's 7mm Rem Mag and case life improved considerably.
603Country is offline  
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 08:40 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
This site and contents, including all posts, Copyright © 1998-2014 S.W.A.T. Magazine
Copyright Complaints: Please direct DMCA Takedown Notices to the registered agent: thefiringline.com
Contact Us
Page generated in 0.08953 seconds with 9 queries