Case head separation?

ShtrRdy said:

I don't know about the Federal ammo being old, but my theory on the primer looking fine is that the case gave way first. That would imply the pressure isn't too much but rather the brass was faulty.

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Tikkas and Sakos as as a general rule have tight chambers and and tight headspace. This keeps the brass from showing primer flow or craters as easily as some other guns that have larger firing pin holes, more headspace etc. Sako and Tikka are well known for shooting over book velocities and not showing pressure signs. The loads are still over pressure but the conventional signs may not show up. Most of you already know that by the time you get case head or rim expansion, ejector marks, loose primer pockets, you are already way over spec pressure in most cases.

You can call it faulty brass if you want but the long and short of it is these loads were far over pressure for the case and components used. DO NOT shoot any more and get the gun checked for scoring, damage to the chamber, bolt etc.

I have actually had RP brass come apart at the head and it actually come clear apart with NEW factory ammo in a 375 RUM for that Reason i try not to use Remington Brass

Tikkamike said:

I have actually had RP brass come apart at the head and it actually come clear apart with NEW factory ammo in a 375 RUM for that Reason i try not to use Remington Brass

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I once bought some once fired range brass from a guy for the 300 Win Mag. This was when 300 Win Mag brass was hard to find. I had a couple cases split down by the Belt - closer to the belt than where a head separation occurs. I cut those cases open and the brass was very thin in that area. The whole web area was thin not just a ring from brass stretching.

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.

I'm going to agree with OhYtD, it would seem more likely to be a problem with chamber dimensions than just over pressure. I've seen more than a few over pressure rounds in a lot of different calibers over the years, most of which I still have (when I could pry it out of the owners fingers!) and I've never seen one that looked like that! Especially with the factory ammo which is seldom anywhere near max in any caliber. Generally, the older it is, the lower the pressure, too, although that's not engraved in stone... (depends on how it was stored). If you can't do it yourself, take the rifle to a smith and have a chamber cast done. This will at the very least confirm the chamber is ok but I'm betting on a bulge near the bolt head.

Depending on the rifle, but especially with a new-to-me rifle, I seldom start that close to max. I like to start out with a powder that has as large a range as possible and start near the middle, just to see what the initial shots look like. If it seems really mild, I might jump a little more on the next load but either way, I kinda sneek up on max charges. Once I'm familiar with the rifle with a few different powders, I might start near max with a known powder but with *anything* else new, start low/mid and work up a bit more slowly. You're more likely to keep all your digits & face in one piece that way!
Cheers,
crkckr

OhYtD said:

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.

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belted cartridges swell right above the belt after a couple of firings and wont fit in the chamber ! inovative technologies has a die that solves this problem ! the die reduces the case about a thousant and thats all you need

If the gun had a bad chamber or excessive head space it should do this with all brass and loads. It only did it with the Federal brass, the rest of the loads using Rem brass were perfectly fine. I agree the gun need to be checked by a good gunsmith but more for damage caused by the gas leaks than an issue with the gun originally.

OP, you have to let us know what you find out after taking it to the gunsmith please.

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!

lancetkenyon said:

I would bet that Federal brass is way heavier, meaning more brass content, meaning less case capacity, meaning higher pressures, than the R-P brass. I have found this to be the case with .243, .260, .25-06, .270, 7RM, .300WM. Federal has had higher brass content which results in higher pressures with the same charge weight that is fine in other brands of brass.
Never substitute components without dropping down and starting over. I bet "book max" is with another brand of brass.

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If that was true then one would think that Federal would allow for that when they loaded and tested the ammo. Also if you tried 20 different powders the fill volume would not necessarily be equal for all of them, so I wouldn't think that case volume would be a major issue.

Ross1147 said:

Totally stock Tikka. If this just happened with the reloads I would be thinking it was something I did but because it first happened with the factory round it has me wondering...would the fact that the factory federals were old (but in good shape) cause them to be overpressure? Also, if over pressure why do the primers and bases look fine? No ejector marks or primer cratering?

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Did you mic the necks of the various loaded rounds to see if they are too tight for the chamber or did any of the rounds that went uh oh chamber hard?

Would be interesting to see if the same issue arises if fired in a different gun. I've fired lots of stuff loaded in Federal cases over the years and never had a case come out looking like that.

Actually I did mic the necks up and there was plenty of clearance.

But I'm pretty sure the first factory federal round effed the chamber up. Just gave it a good cleaning and this is what the chamber looks like...just what I wanted to do, buy a new barrel...

Take the Rem brass, the ruptured Fed brass, any unruptured Fed brass and the gun to a smith. There is not enough info available to tell you for sure what is going on by remote diagnoses. I do not see any evidence of thinning or bulging on the perforated brass or the other one. Brass that is too soft at the base, case capacity, too thick a neck, all could be the issue or part of it, but so could a whole raft of other things. You need an expert to look at and diagnose the issues. Like I have said in both previous posts, even if the gun was perfect originally there is a good chance it isn't any more.

P.S. Just saw your latest post. Definitely needs to be looked at. If it was the factory round, and that is what I would be talking to the smith about, I would be talking to Federal Ammo.

Do you see any markings/etching on the fired cases that didn't blow that would indicate that the chamber has rough spots in the area where the gases escaped?

No none? I took a few pieces of brass and the gun to a smith I have down the road. He's going to scope it for me but he thinks it's fine. Let's hope!