270 WSM What caused this?

[JMUPT]

A few months ago I picked up a savage model 11 FHNS at an auction, it was just about brand new. Well this past weekend I finally got around to putting a scope on it and loading a few rounds to sight in with. My load was 59 gr of IMR 4350 with a 130 gr Nosler AccuBond with a remington large rifle magnum and new winchester brass, which was a starting load for this power according to the Nosler book. Well I went out and fired the first 3 rounds a about 35yds to get it on paper with no problems and then moved out to 100 to finish up sighting it in. Rounds 1 and 2 were about 2 inches apart and the cases looked fine no pressure signs then on round 3 I pulled the trigger and heard click, ejected the shell and the primer had been hit but not as hard as the others. Put the round back in and it went off this time when I pulled the trigger. Everything seemed normal except I had a hard bolt lift and ejection, when the case came out it had a crack in it about 1/2 inch up from the base and about 1/4 inch long it. The case also had 2 dents in it below the neck on oppisite sides (this could have came from the table when the case was ejected but I doubt it). The primer was also flatend, it sounds like a over charged case, but I am 99.9 % sure that I did not over charge the case, I loaded the cases 1 and a time and weighed each charge and they were the only rounds on the bench. I had 2 rounds left so I waited a while and then fired the remaining 2 rounds, but the last round I fired went click the first time I pulled the trigger, primer had been hit again but didn't go off. Put it back in and it went off with the second pull of the trigger. I inspected the case and it was fine except a mark in the case in the same place as the other case that cracked open. I will try to post pics of the cases so you can see them but it might be a day or so. I talked to a buddy of mine and he said it might be a headspace issue but I wanted to see what everyone else thought. Thanks for any help you can provide.

 

[YoteSmoker]

Headspace issue is the first thing that comes to mind. Since it's a Savage, they are easy to work with if you have a barrel vise and action wrench and a set of go/no guages. If not, have it checked by a gunsmith. Also, did you neck size or full length size the brass? Be sure not to set the shoulder back too far or this could also contribute to the problem.

 

[Antelope_Sniper]

I'd be inclined to go with Yotesmoker on this this one. A set of Go/NoGO gauges might be a good investment.

 

[Desert Fox]

Is this rifle has the Accutrigger? If so, then the problem is not in the headspacing but in the trigger. I read a similar problem from one Savage owner on another forum.

Here's the thread.

http://www.snipershide.com/forum/ubbthr ... w=1#UNREAD

 

[Antelope_Sniper]

Yea, but that doesn't explain the split case.

 

[BK]

No help on the split case, but since you don't really know the history, I would yank the guts out of the bolt and make sure it's not all gummed up.

 

[DrMike]

To get separation of the case near the web would almost certainly require a problem with headspace. Go/No Go gauge will quickly tell you on this point. It might be worthwhile to have a competent gunsmith do a cerrocast of the chamber if the headspace appears to be correct. If you check the other cases that were fired, running a paper clip on the inside of the case to check the area immediately above the web, is there evidence of incipient case separation?

 

[Guest]

Maybe I'm reading this wrong, but it sounds like the original poster had a case split longitudinally, rather than circumferentially. If the split is along the case, running from head to shoulder in orientation, as I believe, it's not a headspace problem.

I'm thinking outside the box on this, but is there a chance the round was short charged? If the charge were sufficiently low, it could give you exactly the result found here. The first tap of the primer was not sufficient to ignite the powder, and the second strike ignited it across the top, building multiple flame fronts and causing isolated pressure spikes. That would explain the split, as well as the dented shoulder (I saw a 44Mag case that was dimpled like a golfball once...) and the stiff bolt lift.

I'd inspect carefully and clean the bolt body and firing pin/spring. I'd also inspect any and all handloads you've got left to be sure there's no issues there. Inspecting the chamber would be good, as well.

Beyond that, I can't imagine what could have happened, unless you're crimping the bullets too tightly and ending up with a little shaved copper jacket in the chamber and that's where the problem lies.

 

[JMUPT]

Thanks for the responses so far, Here are some pictures so you can see what the cases look like. In the pictures with all 3 cases the one on the left looks to be normal, the middle one is the last round that I fired ( pulled trigger and click, put it back it and went off on the 2nd pull of the trigger). The case on the right is obviously the one that ruptured and has the flattened primmer. I'm not sure how to post pictures small enough so I just put them on photobucket and here is the link.

http://s808.photobucket.com/albums/zz5/ ... M%20brass/

Let me know if you still think it looks like a headspace issue, I also didn't realize an under charge may have caused this, but thanks for the idea.

 

[DrMike]

The picture shows a bright ring on the centre case, indicative of incipient separation of the case head. You can likely feel this beginning to separate by using a paper clip pushed down into the case. It does look as if you are experiencing a headspace issue.

 

[Antelope_Sniper]

I'm with DR Mike on this one.....looks like a headspace issue.
As previously mentioned, Savages are easy to work on. If you get a set of headspace gauges, there are several video's on youtube on how to properly set the headspace on Savages....or you can take it to your gunsmith.

 

[Guest]

After looking at the pictures, it's not what I originally thought. The split goes around the case, and that means headspace, just as Dr. Mike and Antelope Sniper have said. These were once fired cases? Or brand new brass? Or multiple-fired? If they're new or once-fired, I'd say headspace. If they're multi-fired, and have been full-length resized a couple of times, I'd say get a neck die and use it, or learn how to properly partial-FL size with your existing die.

I'd have a gunsmith check the headspace just in case, as it's about $20-30 to have it done, and it's cheap insurance.

 

[NTM]

I've had brass dent like that on my 7mm rum one time when I was just beginning to work up a load-was caused by too light of a load. I've had Federal brass seperate on me like that on more then one rifle where the headspace was known to be good.-Just food for thought.

 

[JMUPT]

Thanks for the input, One more question for you? Should I ship the rifle back to savage to have them fix it on their dime, instead of spending my own money on a firearm that left the factory in this condition. I have been out of town lately and haven't had a chance to talk with savage yet. Thanks again for the help.

 

[DrMike]

I'd certainly speak with them. At the least it is a courtesy to permit them opportunity to address the problem. I would be greatly surprised if they did not want to make things right.

 

[woods]

Classic case of case head separation. The dent at the case body / shoulder junction is where the gases escaped from the separation out along the case body for egress out the muzzle. Almost always present with case head separations

If these were multiple loaded cases then you need to not push the shoulder back so far. If these are new cases then you have a much bigger problem and would most likely be because of excess headspace and/or too light a load.

My guess is you are pushing the shoulder back too far.

 

[JMUPT]

These are brand new winchester cases, if it was a headspace issue would it show on all rounds fired or just random ones?

 

[DrMike]

If the chamber space is not terribly out of specs, it would be magnified by any case that had a weak point. Hence, the deficit could appear to be random. Have Savage check the rifle out and ensure that it is properly head spaced.