Incepient case head seperation after 3 loads.

[fguffey]

Jerseyjoe, forgive, If I am not serious and or it did not happen I start with; "You are not going to believe this", or "Now hear this" and then there are times "Listen up men" works and then there is the Air force story and the old army story, "Me and my buddy were etc..

Anyhow, if you have no objections we can compare notes on the phone. Let me know.

F. Guffey

 

[Webster]

I recently purchased a browning a bolt in 270 winchester. After 3 firings on brand new winchester brass i noticed the famous ring around the web but only on one side. I cut one in half and sure enough there seperating but only on one half, i looked at other cases and they have a sharp bulge on half of the case almost like one side of the chamber is outta round. Im fl sizing and am only moving the shoulder .001" so they chamber. All cases are doing this with light loads or max loads. No diffrence in them. Im usally shooting 59gr of h4831 with a 130gr accubond. Im stumped and it sucks only getting 3 reloads before trashing the case.

100 replies and he is still looking for an answer.

 

[dkhunt14]

100 replies and he is still looking for an answer.

Sometimes without having or seeing the gun, dies or brass it is not possible to give a correct answer. I did see lots of answers that are probably correct. If a case is separating, it is too much headspace. You are bumping the shoulders too much. The bulges in the case are probably from a bad chamber or bad brass. If they are not straight, it could be action not true to bolt face or brass thicker on one side then another. These answers were all given and some more then once. Matt

 

[Brians356]

If a case is separating, it is too much headspace.

The photos of the outside of the cases, and the sectioned case, dispel the notion that the cases are separating.
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[Mtstalker]

New brass will be here saturday. I triple checked everything. Shoulder bump is .001" die is sizing .002" smaller than fired(in diameter). Measured fired case with sinclair "headspace" guage (primer removed) and its about .003" above min sammi spec for chamber and spot on for case specs new cases range from .004" to .007" shorter than fired its actually well below what sammi has listed for case size even with there plus or minus numbers . So far everything is pointing to a bad batch of brass. I measured a case i cut in half and wall thickness varies by up to .003" from one side to another in 4 loactions i measured on the brass all were measured on the spot on both sides. If this problem persist with new brass that is a bit fatter in the web area i will take it to a gunsmith to have the chamber checked out. I will do a update once i have fired and sized the new stuff. Luckaly the range is only a half mile away so i can make mutiple trips to get a few loads on the brass. And yes the cases havent seperated yet but they are on there way to seperating. The brass in the thin spot measures .016" when on both sides of the dimple it measures .028" . There is a whitish flaky looking ring right above the ridge in the brass. I have a handfull of cases that have seperated from 10+ loads. If you would like Brian356 i could send you a few and you would probaly say there fine but im not risking getting hurt because some guy on the net said it was fine. There getting trashed and thats that.

 

[Mtstalker]

Here are some cases from a rifle that did have a head space issue. From new to fired theres a .020" diffrence its 300 win brass. The non split has one load the split case was the second firing.

 

[Mtstalker]

Wish i would have found this a few days ago.
https://www.google.com/url?sa=t&sou...n7h_8OcVLVIf00kBg&sig2=yhjwFc4ct38UUecjq5yKbQ

 

[dkhunt14]

Wish i would have found this a few days ago.
https://www.google.com/url?sa=t&source=web&rct=j&url=http://www.4-dproducts.com/submenu/That%20Unsightly%20Bulge.pdf&ved=0ahUKEwicotKouOHRAhVLxFQKHVS8Cf0QFggkMAE&usg=AFQjCNGaSv86-Pjwmn7h_8OcVLVIf00kBg&sig2=yhjwFc4ct38UUecjq5yKbQ

I don't know if I totally agree with everything in that article. I see the chamber as an oversized die. When you hit it with 50 to 60,000 PSI, the case will form to the chamber. It might take a shot or two to fully do it, but it will get there. I believe if you have a bulge in the case, it is the chamber is too big or something else like alignment is the problem. Matt

 

[Mtstalker]

Yes i agree but there is some good info.

 

[mac86951]

Sorry quote didn't come over nicely. In response to catching brass defect at manufacturing...

Lol! In current state of manufacturing; best that can be said is maybe or maybe not. To be fair, all companies have had some form of escape of quality defect; good ones handle it better and are fewer and far between. In this world; it's best we trust but verify since ultimately we are responsible.

This doesn't mean point the finger at the manufacturer; instead just don't rule them out as a potential contributor to the problem. The Manufacturer may be a good resource of information during the troubleshooting process; likewise, may indeed wish to collect lot number information from you as they may have more info and useful product checks.

 

[fguffey]

Here are some cases from a rifle that did have a head space issue. From new to fired theres a .020" diffrence its 300 win brass. The non split has one load the split case was the second firing.

Case head separation caused by excessive head space: Where was the excessive head space? And then there is the .020" difference; difference in what?

F. Guffey

 

[Mtstalker]

In case length from the head to the datum line.

 

[Mtstalker]

New brass showed up and i fired a few and sized them and shot again and the ugly ridge is not present. They measured only .002" smaller than my fired cases out of the bag. That problem has been taken care of. Now i am in the process of re working the load because i ran charges untill i hit max in the gun and its quite a bit less than the winchester brass. Thanks for your input guys.

 

[jerseyjoe]

Glad it was a relatively easy fix.

Safe shooting!

 

[Mtstalker]

Thanks Jerseyjoe.

 

[fguffey]

Case head separation caused by excessive head space: Where was the excessive head space? And then there is the .020" difference; difference in what?

In case length from the head to the datum line.

100 replies and he is still looking for an answer.

I am not surprised Webster was not all over this one;

Stoop429, .020" increase in length from the shoulder to the case head would seem to enough to cause case head separation. We both know the belted case head spaces on the belt. What most do not understand is head space can be measured in the chamber in thousands; the tough part is convincing someone it can be done. So, according to the information provided by your chamber allows the case to move forward .013" more than it should.

After that it gets complicated because the belt specifications for the case from SAAMI says: .220" and .212" is acceptable. Case manufacturers do not make cases for reloaders that know what they are doing, if the did I could choose a case with a thicker belt to off set the chamber head space. If you chamber has the additional .007" and you case belt is on the thin side you can have ..015" clearance.

And then we have to go back to that part reloaders have a lot of trouble with; they claim the shoulder on the case moves and that is not an absolute. If the belt on your case held the case to the rear the shoulder on you cases would not have moved. The shoulder would have formed to the chamber and the shoulder on the ejected case would be a new shoulder BACAUSE THE SHOULDER DID NOT MOVE; meaning length would have been added to the case from the shoulder to the case head.

What does this mean?

F. Guffey

 

[Mtstalker]

Yes thats what i was trying to say that the increase of .020" in length caused the seperation that you can see in the pictures. The first firing stretched the case just enough that on the second firing they did seperate. But i was taught that with belted magnums such as the 300 win the case headspaces off the belt on the first firing then after that its off the shoulder. In books ive read it says they always headspace off the belt never the shoulder. Which one is correct? Yes i know when we say "bump" the shoulder were not moving the shoulder without changing the cases body were ever so slightly shortening the body which makes shoulder sit farther away from the shoulder that has been cut in the chamber.

 

[SheepDog]

For all belted magnums except the H&H magnums you should size the case to headspace off the shoulder. This will prevent case head separations and your brass should last at least 10 reloads.

 

[Mtstalker]

Sweet so i was told correct.

 

[fguffey]

Sweet so i was told correct.

Wait a minute; A thicker belt would prevent the case head/belt from moving forward. Back to your 300 Win Mag chamber. If you sized your cases to head space the shoulder of the case against the shoulder of the chamber you could create another problem. This has never been discussed before but if you have excessive clearance on the belt and the case is shoved back berceuse it head spaces on the shoulder of the chamber the case body in front of the belt is not supported.

No problem, there is therapy in the form of a collet die.

When the case in front of the belt is not supported there is a big chance the case would increase in diameter in front of the belt when fired. Reloaders insist the firing pin drives the case forward to the shoulder of the chamber, never mentioned is the primer. I have killer firing pins, my killer firing pins are like setting at a red light when you get his from the rear. The rear bumper is rendered scrap and the front bumber is still 'like new'. So there is now way my primers can out run the firing pin, my firing pins crushes the primer before their little buddies, the case, powder and bullet know it was hit.

And then there is ammo I have inspected, the primers were hit at least 5 times in 4 different rifles with out busting the primers. 5 cases out of 20 R-P 30/06 cases failed to fire out, all of the primers had heavy dents. I measured the length of the cases from the shoulder to the case head and found the case length from the shoulder to the case head did not shorten.

I then tore down the cases into components, I was impressed, I removed the primers and found nothing wrong except for the dents. I installed the primers back into the same cases and then chambered them, one by one in one of my M1917s and busted all 5 primers. I then measured the length of the case again and the case did not get shorter because of the firing pin strike or being hit from the rear with the primer. And when I ejected the cases the primers were not protruding.

F. Guffey