Case head separation?

[antelopedundee]

The only thing I know of that will do that is excessive head space. Used to see in in belted cartridge's. Because they head spaced on the belt, many chamber's were sloppy and the case constantly moving forward when fired, pulled on the case just in front of the head, belt. In the belted cartridge you see it develop as a ring all the way around the case at the head. You probably won't notice in a rimless case because it just doesn't happen much, better cut chamber's. I think you said your were using them in an auto? By partial sizing you can move the shoulder forward a bit and stop all the stretch. Probably be a good idea first to take it to a gun smith and check the head space. The gunsmith could probably fix it by shortening the chamber.

Keep in mind that a ring around the case head like that is caused by the case stretching to much. You can take unfired case's and shoot them in there and no problem. But, with an unfired case the problem doesn't do away, it simply hide's as it's gonna take two to four firing's to get to that point. Look at your other case's in the same spot and look for a ring all the way around the head. They will be the one's that are fixing to have the same problem.

Case head separation from excessive headspace usually appears as a concentric ring around the case about a 1/4 inch from the rim. I've never seen them appear like that. One thing to try would be to partially pull a bullet from the old box of Federal ammo that gave the problem and reseat the bullet until it just chambers using some effort so that the bullet will jam in the lands and the case won't be able to move when fired. If the OP is hesitant he can fire it by putting a long string around the trigger and using that to fire it from a safe distance. If the result is the same then it's likely something about the cases.

 

[Dean2]

Case head separation from excessive headspace usually appears as a concentric ring around the case about a 1/4 inch from the rim. I've never seen them appear like that. One thing to try would be to partially pull a bullet from the old box of Federal ammo that gave the problem and reseat the bullet until it just chambers using some effort so that the bullet will jam in the lands and the case won't be able to move when fired. If the OP is hesitant he can fire it by putting a long string around the trigger and using that to fire it from a safe distance. If the result is the same then it's likely something about the cases.

Sorry but this is really bad advice. NEVER intentionally shoot rounds you have had previous problems with. There are a hell of a lot safer ways to check headspace, it is what Go/no-go gauges were made for.

 

[antelopedundee]

Sorry but this is really bad advice. NEVER intentionally shoot rounds you have had previous problems with. There are a hell of a lot safer ways to check headspace, it is what Go/no-go gauges were made for.

I'm not convinced that it's a headspace issue. Headspace likely wouldn't give a pattern like that esp. with multiple ruptures. I guess he could send the ammo to a lab that has the setup to fire it safely. Frankly, I wouldn't have any issue doing it if I thought it was necessary. It could check out fine with the gauges, but still have a headspace issue if the cases were somehow too short. At this point I would send pics of the case and ammo box and the lot number from the end flap of the box to Federal and ask if they had any issues with this lot and their thoughts about a cause. They would likely want the rest of it back along with any cases from the other lot of Federal cases that he said acted the same way.

 

[antelopedundee]

[QUOTE="Ross1147, post: 1659067, member: 106919" So I agree that it was some kind of overpressure but I don't think it was an overpressure for the gun if that makes since? I haven't been reloading as long as some of you guys but I've been doing it for a long time now and in my experience if your using a coal way over SAAMI you're increasing the case volume for a given bullet therefor pressure will be lower than what the book lists for a given powder charge. Now I know there are other factors like bullet jump, tight chamber, copper fouled barrel, etc. The Berger's I loaded were right smack in the middle of Berger's data for the 180 EH (38.0-42.4 grns IMR 4895). Velocity around where I expected (38 is 2385fps and 42.6 is 2641fps. At 40 grns I saw 2450ish). I'm really leaning towards camber bulge or something now.

I cut 2 cases apart to see inside and what was going on. The one on the right is the factory case that I pictured in the first post. One on the left is a twice fired FC from the same lot I shot the Berger's with. Both look fine to me..brass looks nice and thick at the case head.

Another random fact is all three cases that split were 180 grn bullets. This was the first time the gun has ran 180s and all 3 split. Not sure that's important at all but I found it interesting. Also, if the chamber is bulged would I be able to tell if I look at the first brass I shot in between the issues I had? Thanks![/QUOTE]

If a max published load has a safe working pressure and you reduce the load 5 times by 1 grain each time aren't you reducing the occupied volume and in effect increasing the case volume; yet those loads continue to show decreasing pressure?

Odd that the cases survived 2 normal firings, but turned to chit in the Tikka 3.

 

[Ross1147]

No, the case volume stays the same no matter what the charge in there as long as the bullet doesn't move. Think of it as a gas tank. If I have a 30 gallon tank and I have 25 gallons in it it's still a 30 gallon tank. If I have 20 gallons it doesn't change the fact that it is a 30 gallon tank. Now if I move the top of the tank down (bullet) it now becomes a 25 gallon tank. So what use to be a 83% full tank (25/30) is now a 100% full tank (25/25). Moving a bullet into the case reduces volume and pulling it out of a case increases volume. So a 180 grn bullet loaded to a coal of 2.824" is taking away more volume in the case then if I loaded it to a coal of 3.000".

No idea why the case split from a factory load and why it split from the reloads? The smith I took it to today and showed the brass to said he would put money on it being crap (brittle in his words) brass. He'll scope it and get back to me Monday. Either way the brass is in the garbage and I've got new 308 brass trimmed and primed waiting to be reloaded once I get the news on he gun. In the mean time I've got a new 6 Dasher I need start fire forming brass for. Thinking I'm going to make it into my new coyote gun!

 

[antelopedundee]

No, the case volume stays the same no matter what the charge in there as long as the bullet doesn't move. Think of it as a gas tank. If I have a 30 gallon tank and I have 25 gallons in it it's still a 30 gallon tank. If I have 20 gallons it doesn't change the fact that it is a 30 gallon tank. Now if I move the top of the tank down (bullet) it now becomes a 25 gallon tank. So what use to be a 83% full tank (25/30) is now a 100% full tank (25/25). Moving a bullet into the case reduces volume and pulling it out of a case increases volume. So a 180 grn bullet loaded to a coal of 2.824" is taking away more volume in the case then if I loaded it to a coal of 3.000".

No idea why the case split from a factory load and why it split from the reloads? The smith I took it to today and showed the brass to said he would put money on it being crap (brittle in his words) brass. He'll scope it and get back to me Monday. Either way the brass is in the garbage and I've got new 308 brass trimmed and primed waiting to be reloaded once I get the news on he gun. In the mean time I've got a new 6 Dasher I need start fire forming brass for. Thinking I'm going to make it into my new coyote gun!

I would mic the brass around the case head in the new and fired Federal cases. Do the same for the other cases which caused no problems. It could be that the Federals were accidentally sized with a small base die and now the area above the bolt face that surrounds the case head when it is chambered does not sufficiently support the the case and allows it to expand some resulting in the splitting that you see. Seems like your best solution is to avoid Federal brass. Remove the bolt and lock a case into it as as though you were chambering a round. You or your smith should be able to tell if the clearance between the case head and the bolt wall surrounding it is within factory spec.

 

[antelopedundee]

No, the case volume stays the same no matter what the charge in there as long as the bullet doesn't move. Think of it as a gas tank. If I have a 30 gallon tank and I have 25 gallons in it it's still a 30 gallon tank. If I have 20 gallons it doesn't change the fact that it is a 30 gallon tank. Now if I move the top of the tank down (bullet) it now becomes a 25 gallon tank. So what use to be a 83% full tank (25/30) is now a 100% full tank (25/25). Moving a bullet into the case reduces volume and pulling it out of a case increases volume. So a 180 grn bullet loaded to a coal of 2.824" is taking away more volume in the case then if I loaded it to a coal of 3.000".

No idea why the case split from a factory load and why it split from the reloads? The smith I took it to today and showed the brass to said he would put money on it being crap (brittle in his words) brass. He'll scope it and get back to me Monday. Either way the brass is in the garbage and I've got new 308 brass trimmed and primed waiting to be reloaded once I get the news on he gun. In the mean time I've got a new 6 Dasher I need start fire forming brass for. Thinking I'm going to make it into my new coyote gun!

The loading manuals usually give a COL along with their data and I don't thing it changes with charge weight so reducing the powder charge has the effect of increasing the amount of empty space in the loaded round.

 

[antelopedundee]

No, the case volume stays the same no matter what the charge in there as long as the bullet doesn't move. Think of it as a gas tank. If I have a 30 gallon tank and I have 25 gallons in it it's still a 30 gallon tank. If I have 20 gallons it doesn't change the fact that it is a 30 gallon tank. Now if I move the top of the tank down (bullet) it now becomes a 25 gallon tank. So what use to be a 83% full tank (25/30) is now a 100% full tank (25/25). Moving a bullet into the case reduces volume and pulling it out of a case increases volume. So a 180 grn bullet loaded to a coal of 2.824" is taking away more volume in the case then if I loaded it to a coal of 3.000".

No idea why the case split from a factory load and why it split from the reloads? The smith I took it to today and showed the brass to said he would put money on it being crap (brittle in his words) brass. He'll scope it and get back to me Monday. Either way the brass is in the garbage and I've got new 308 brass trimmed and primed waiting to be reloaded once I get the news on he gun. In the mean time I've got a new 6 Dasher I need start fire forming brass for. Thinking I'm going to make it into my new coyote gun!

Any update on what the smith had to say about it?

 

[Ross1147]

He still has it. They told me 100% they'll look at it this weekend. I'm not holding my breath.lol

 

[antelopedundee]

He still has it. They told me 100% they'll look at it this weekend. I'm not holding my breath.lol

Did you pull any bullets from the old box of F C ammo? Was the powder good or the bullets or primers corroded

 

[aushunter1]

I recently bought 3 x 20 boxes of Fed powershok 300wsm for a new rifle & out of the total of 60 30 of them wouldn't even chamber which is pretty ridiculous for factory ammo.
I checked the length to the datum & it was .020 over the max SAAMI spec length.
Not only that with the ones that I could fire I was hoping to use them for reloads but all when trying to seat some Fed 215 primers the primer pockets are so lose I am a bit fearful they will pop on firing.
Not happy but I think I will be binning them.
Luckily I bought 100 Norma to use for my LD, its pretty good quality & the primer pockets are super tight which means I should get a decent amount of reloads out of them.

I have used Feds in my 22-250 & not had any problems?

 

[antelopedundee]

I recently bought 3 x 20 boxes of Fed powershok 300wsm for a new rifle & out of the total of 60 30 of them wouldn't even chamber which is pretty ridiculous for factory ammo.
I checked the length to the datum & it was .020 over the max SAAMI spec length.
Not only that with the ones that I could fire I was hoping to use them for reloads but all when trying to seat some Fed 215 primers the primer pockets are so lose I am a bit fearful they will pop on firing.
Not happy but I think I will be binning them.
Luckily I bought 100 Norma to use for my LD, its pretty good quality & the primer pockets are super tight which means I should get a decent amount of reloads out of them.

I have used Feds in my 22-250 & not had any problems?

What did Federal have to say? Try seating a primer and tapping the rim on a hard surface at an angle. If they are really loose the primer would likely fall out.

 

[wwbrown]

I am not convinced that the round shown that failed was over pressure for sound brass. I don't see any brass flow into the ejector and the primers do not seem to have a lot of flow either for the a factory gun with factory clearance on the firing pin. Unless you are shooting brass like Lapua brand 338 Lapua Magnum brass most brass will exhibit at least "ejector swipe" when overpressure. I would not be surprised if some of the other premium brass companies may also not show ejector swipe when overpressure.

I have seen a couple, or more, examples of failed brass in over 4 decades of reloading but never this type of failure mode. Others have already identified that the fact that this is not the standard case head separation correctly describing what most of us refer to as case head separation. It is very easy for us to say any brass failure is due to overpressure and in some sense that is correct, for that piece of brass the pressure was too great, but could have been well under SAAMI specs but over what that piece of brass could handle.

As an example, you can treat this as a thought experiment or actually go out and test it in the field. Please use a full face shield if you test in the field. Bump your shoulders back 50 thousands beyond what you should for your chambering and put a minimum load of powder. This case will probably have a case head separation yet the chamber pressure is well under max values. I bring this example because it is not a great help to a reloader who is new and finding their way to just chime in saying that round is over pressured for a case head separation. The root cause of most case head separations is, as has been stated by number of others before me, is due to excessive headspace which is usually due to following the die manufactures method for setting dies up. Telling a reloader with case head separation that they have to reduce their powder charge without adjusting the amount they are bumping the shoulders is not a help as the reduced powder charge is apt to cause the same case failure as it was not the root cause of the problem.

As I stated earlier the pressure was clearly too high for those pieces of brass, but not necessarily for that cartridge and firearm.

As an aside I no longer reload Federal brass and probably have not for 25 years or so as I find it too soft. If I recall correctly I learned how soft Federal mainly from 223 brass, blowing primers on one reload in 223. Other calibers may not have been as soft, although they probably were not pushed as hard as I did the 223's, but all calibers seemed to loosen the primers earlier than other brass. In the succeeding almost 3 decades maybe Federal brass is not as soft as it was, others may be able to chime in on this.

 

[Ross1147]

Did you pull any bullets from the old box of F C ammo? Was the powder good or the bullets or primers corroded

No, I tossed the box on the couch in my reloading room and it's still sitting there. Got caught up reloading for my new Dasher. I'll pull one tomorrow to see what it looks like.
No call today from the gunsmith. I doubt they'll get to it this weekend. I was trying to get the gun back to my dad this weekend because I may not see him before deer opener. Oh well, he's got his backup gun I guess.