Split Cases and No pressure Signs before?

[TN deer hunter]

I have been loading my .280 with 58.5gr of RL17 and the 120gr BT. Accuracy and speed have been outstanding. I checked the speed on these this spring and the temp was about 65 degrees, Saturday the temp was 58. I had not had any pressure signs until Saturday. I shot three shots and didn't notice any pressure signs until the last shot, the bolt was stiff and the case had split around the case and not along the length. Looked at the other two and my second shot had slightly split as well. I clean the gun good and then dropped a grain to 57.5 and shoot again yesterday and the first shot was with a factory shell (Hornady Light Mag. 139gr SST )to foul the bbl and it was fine. My next two are nearly touching and I think this is going to be ok, no flattened primer or anything then my last shot the case splits so I go load another shell using new brass and shoot it. The case didn't split but you can see a white colored crooked ring around the case where the others had cracked. I don't understand I have had no pressure signs at all. I thought the brass may have been loaded too many times but the new brass threw that out. I also noticed that these happened when I used a new box of Federal GM210 primers but I wouldn't think a different lot of primers would built up that much pressure. The cases were Remington anyone have any ideas?

I posted this on another forum and someone suggested that my die needs to be backed off to just touch the shoulders....BTW Its a new Steyr Prohunter. I have had it for about 4yrs but just started fooling with it last year. Thanks for any suggestions or help!

 

[RiverRider]

I agree with the previous suggestion that it may be a headspace issue. If your getting casehead separtation with brand new brass, something's definitely not right.

Have you had casehead separation with brand new brass on the first firing? Do you resize brand new brass before loading it up?

 

[DrMike]

For certain, I'd have the rifle checked by a competent gunsmith. The case failure doesn't sound like a problem caused by faulty brass, though that cannot yet be ruled out. 58.5 grains may be tickling the dragon's tail, however. Out of curiosity, what sort of velocities were you getting?

 

[Guest]

How many times has the brass been resized and fired? It sounds like you're close the the max spec on the chamber, and your fully resizing your brass, which is creating the headspace issue. Or perhaps your rifle is out of spec. Of course, since the factory Hornady brass didn't do this, it sounds more like die adjustment than anything else.

 

[TN deer hunter]

Wouldn't there be issues with factory ammo as well if its a head space issue? Last year I loaded 139gr SST's, 120BT with RL19 and never had a issue. The 139gr load was over max and I did get pressure signs before backing off and settling on a load....wouldn't I have had a problem then as well?
Tonight I will break out some new brass and load up some new rounds and shoot them tomorrow, I will then work with my die and see if this is the problem. I have had this gun for 4yrs but never shot it much or fooled with it until last year. Those 120BT's sure do shoot good and fast with 58.5gr of RL17 I hope its just a die issue! Thanks for all the replies. I will keep you posted on my findings.

 

[Ol` Joe]

Case seperation can be an accumulative event if you are pushing the shoulders back too much when sizeing, or if headspace is bad enough it can come all at once. Just because factory ammo didn`t split doesn`t mean excessive headspace isn`t present somewhere in the system.
Normally brass splits along its lenght if pressures are too high, necks split from work hardening and seperations at the web are a headspace problem. This isn`t cut in stone and you shouldn`t take it that way. It is the most common causes of the failures though.
Bolt lugs can set back too from repeted heavy loads, causing excessive headspace to develope. I`d get a headspace gage and check my brass both before and after fireing to see if there is a lot of movement in their boltface to shoulder datum lenght. Stoney Point, now Hornady makes a reasonably priced one that fits on your calipes and is IMO a must for every reloader.
http://www.midwayusa.com/viewProduct/?p ... ber=479704

 

[Greg Nolan]

I agree with Ol`Joe.
Case stretch from excessive headspace isn't too uncommon if over pressure loads set the bolt back. Especially if one lug is taking the preponderance of the pressure untill contact is made with both lugs. You mentioned outstanding velocity. Factory ammo is loaded with different powders and the pressure my not peak fast enough to split the case.
A go/no go guage check should tell if that's the problem. Improper die adjustment could sure make the results your getting show up quick.
Greg

 

[old #7]

You should cut one of your cases in half. Just because it didn't split doesn't mean it hasn't been substantially weakened. I used a dremel tool but I suppose a guy could use a hack saw with a fine blade and a light touch.

 

[Innovative]

TN deer hunter .......

Check out this article about headspace separation. It explains why it happens and how to avoid it.
http://www.larrywillis.com/headspace_separation.html

- Innovative

 

[TN deer hunter]

Time for a update....I loaded three different loads 57.5, 58.0, and 58.5 all with new brass with the exception of one and that was one of the 57.5 cases. Temp was 60 degrees. I started with the 57.5 load, fired two shots no marks on cases or flattened primer's everything was good. I then fired the last 57.5gr load in a new case that I had run through the re-sizing die. This case had a flattened primer. Next, I fired the 58.0gr load primers were a little flattened but all three shots grouped 1/2". I stopped with this load and did not shoot the 58.5. I think I'm going to stick with the 58.0gr load and watch for pressure signs. I now need to set up my die. The procedure I used before was to screw the sizer die down until it touched the the shell holder then turn it 1/4-1/2 more.

 

[Innovative]

TN deer hunter .......

If you setup your dies according to the die manufacturers instructions, things usually work out very well. However, not all chambers are the same, and not all dies are the same either. That's why it's especially important to "measure" the clearance (at the shoulder) that YOUR handloads have in YOUR particular chamber.

There's only one thing that causes cases to crack above the base, and that's excessive headspace. It's very common even for mild loads to rip cases in half. That's called headspace separation.

- Innovative

 

[old #7]

Cut that case in half lengthwise and post some pics.....please.

Next, I fired the 58.0gr load primers were a little flattened but all three shots grouped 1/2". I stopped with this load and did not shoot the 58.5. I think I'm going to stick with the 58.0gr load and watch for pressure signs.

Another question I have is...

I started with the 57.5 load, fired two shots no marks on cases or flattened primer's everything was good. I then fired the last 57.5gr load in a new case that I had run through the re-sizing die.

What was the condition of the previous two cases? once fired , twice fired, ect.