What did I do wrong? (Case failure.)

[Jim B in CO]

I was at the range today shooting some .308 out of my R700 (SPS Stainless with no modifications). On the ninth round I noticed the bolt was a bit more difficult to open than the other rounds. It didn't take long to determine the cause - the case had split on one side. It's FGMM brass (not plated), Nosler Custom Competition 168s (#53164), 43.4 grains of Viht. N140, Remington 9-1/2 primers, 2.810" COAL. This was the sixth time this brass was fired. It was full-length sized after the first and fifth firings and neck-sized the other times. Nosler lists the max. charge of N140 for that bullet as 44.5, so I wasn't too close to the limit. The other loads I've fired out of this brass were probably quite a bit milder than what I was shooting today. All the charges were weighed on an RCBS ChargeMaster; I'm pretty sure the case was not overcharged. I visually inspect each case 2-3 times after I've charged them and before I seat the bullets.

I bought the rifle used but in very good condition with hardly any signs of wear. I've fired 300-400 rounds through it without any problems, so I don't think there's anything wrong with the rifle (i.e., excessive headspace or something like that). It seems I used the brass one too many times (although six times doesn't seem excessive for a bolt gun). Is there anything else I did wrong?

Thanks in advance!

Jim

 

[kyshootnman]

I had a similar problem with a 260. I had switched up bullets and saw a huge spike in pressure. I would start by checking the length of your brass. I wouldn't think it'd be possible for your OAL length to be in the lands.

 

[Rthur]

"This was the 6th time this brass was fired" From what the case looks like this statement has the answer. I'm guessing you are oversizing your brass. FGM brass is know to be on the softer side. I would say this is a classic case of head separation. That being said you will want to inspect your other cases. A common method is a paper clip with a small "L" bent into the end then sharpened. Insert it into the case as to reach the bottom. Angle it to scratch the side wall and pull out slowly. You should feel the thin spot that has formed in the side wall. If you do discard these cases.

R

 

[BuzzBoss915]

Either you oversized the brass, or more likely, this rifle has excessive head space. I wouldn't fire it until you determine your headspace or take it to someone who can do it for you. BB

edit: the problem is that one of these times, you will extract the case head and leave the rest stuck in your chamber, and this can be very difficult to remove. Your barrel is not set properly and you need a professional evaluation to solve it. Good luck. BB

 

[High Binder]

Honestly, I think you're right at the point where that brass should be failing. Six times is right on par for non-NATO FC brass.

 

[wadebrown]

Whenever I see case head separation like that I think the reloader is pushing the shoulder back too far as that is the usual suspect in case head separation.

 

[jbailey]

Whenever I see case head separation like that I think the reloader is pushing the shoulder back too far as that is the usual suspect in case head separation.

+1. My thoughts the same on the most likely cause.

 

[nso123]

I agree that you may be getting toward the end of the life on that brass. I also think that I can see a pretty good ejector mark on it too, so you may be dealing with a combination of problems. Do you have a pic of some of the other fired brass from that load so we can see if there are ejector marks on them too?

 

[sinister]

Whenever I see case head separation like that I think the reloader is pushing the shoulder back too far as that is the usual suspect in case head separation.

Sizing with either a full-length or small base die you only want to push shoulders back about .002".

.003" and more and your case walls will start to stretch and thin on each firing.

Some will say small base sizing is abusing your brass. Pushing the shoulders back .003 or more may be more abusive as the walls thin, contributing to shorter case life.

Thinning from pushing the shoulders back too far:

These cases were deliberately set back .003 to .005 to document stretching and thinning to failure:

 

[arnie19]

Looking at the case thats laying on its side ,are you crimping the bullet or is the mouth of the case getting into the lead of the chamber ? Arnie

 

[Jim B in CO]

I would start by checking the length of your brass. I wouldn't think it'd be possible for your OAL length to be in the lands.

Thanks for all the replies!

That's a good point. After I full-length sized the cases, I checked the length on several (but not all) of them. All the cases I checked were within spec., so I went ahead and loaded them. I'll check the length on the failed case and see if it's okay.

BTW, I should have mentioned, when I saw the case failure I stopped shooting those reloads. I shot another batch of reloads, with FGMM plated brass that been fired twice, that gave me no problems.

 

[Jim B in CO]

"This was the 6th time this brass was fired" From what the case looks like this statement has the answer.

I think you're correct. I'm going to fire my Federal .308 brass no more than four times, then toss it in the scrap pile. Doesn't seem like much to get out of a bolt gun, but I'd definitely rather be safe than sorry. Not trying to start an argument, but I don't think I'm too impressed with Federal's .308 brass. I do have some Federal brass in .45 Auto that works great. (Low pressure cartridge, obviously.)

I'm guessing you are oversizing your brass. FGM brass is know to be on the softer side.

I'm using Lee dies. Do they have a reputation for oversizing .308? I use Lee dies for many calibers (mostly pistol and .223) and I haven't had any problems at all with them.

 

[Jim B in CO]

A little odd. 6 firings, but only FL sized twice. It looks like there's a pretty good ejector mark in the head.

I only FL size when I notice the bolt getting a little difficult to open (to save wear and tear on the brass and, hopefully, produce more accurate ammo by neck-sizing).

Yeah, I noticed the ejector mark, too. It's right in line with/behind the split, so I think the case head may have gotten forced into the bolt face more than usual, due to the split. (I.e., the case head didn't get forced into the bolt face evenly.) Also, because they're such up-close pictures, it looks worse in the pictures than it does when looking at the case. The ejector mark is definitely visible, but I can just barely feel it.

 

[Jim B in CO]

Whenever I see case head separation like that I think the reloader is pushing the shoulder back too far as that is the usual suspect in case head separation.

How do I tell/measure if I'm pushing the shoulder back too far?

 

[Jim B in CO]

Do you have a pic of some of the other fired brass from that load so we can see if there are ejector marks on them too?

There are basically no ejector marks on the other eight pieces of brass. (If there are they're very, very faint.) Five of the other eight pieces of brass were loaded 1/10 of a grain lighter, at 43.3 grains of N140.

 

[Jim B in CO]

Looking at the case thats laying on its side ,are you crimping the bullet or is the mouth of the case getting into the lead of the chamber ?

Those marks are from crimping, I don't think the brass is hitting the leade.

 

[Jim B in CO]

...you will want to inspect your other cases. A common method is a paper clip with a small "L" bent into the end then sharpened. Insert it into the case as to reach the bottom. Angle it to scratch the side wall and pull out slowly. You should feel the thin spot that has formed in the side wall. If you do discard these cases.

Wow, I can clearly see the thin spot around the inside of the case by looking down into it with a flashlight.

 

[sinister]

You need a case gage or a Stoney Point/Hornady LNL case length gage and a set of calipers. If you don't know how far you're pushing your case shoulders back each time you size you're killing your brass life (and may be setting dangerously loose headspace).

This is a drop-in gage:

This is a Stoney Point:

 

[AtOne]

Get a stony point ( Hornady ) headspace gauge and measure your fired case like in the picture above this will tell you what your headspace is on your rifle.
Now grab one of your reloads or pieces of brass you've full length re-sized and measure it the same. The difference between the two is how much your bumping your shoulders back.
The number shouldn't be more than .003 or else your really over working your brass.

The problem is most dies come with instructions on how to set it up in the press but this usually isn't ideal for your rifle and how much you need to bump your shoulder back.

Have a friend that finally started seeing signs of case head separation on his FC brass around the 13th firing but he always made sure to bump .002 to .003 and trim as minimal as he could.

 

[Deadshot2]

You need a case gage or a Stoney Point/Hornady LNL case length gage and a set of calipers. If you don't know how far you're pushing your case shoulders back each time you size you're killing your brass life (and may be setting dangerously loose headspace).

This is a drop-in gage:

This is a Stoney Point:

Drop in gauges can often be a little misleading. They may or may not match the chamber of your rifle. Both can be within SAAMI spec for headspace but if you size so it drops into the gauge, doesn't protrude from the gauge, it may still be a little short for YOUR rifle.

I prefer the Stony Point/Hornady or Sinclair headpsace measuring tools as they will allow you to use the actual chamber dimension in your rifle as a baseline for bumping the shoulder.

My cases still measure well within the SAAMI limits (actually the same as a Go Gauge) and by bumping them only .001-.002" I can get far more than just 6 loadings out of even FC brass.

I use a Forster Shoulder Bump/Neck Size bushing die so my F/L dies are pretty much in storage. I don't bring them out unless I bring back a whole bunch of once fired brass from the range that others have left behind. (Yes, there are still a lot that don't reload).

 

[Jim B in CO]

Thanks again for the replies.

I'm definitely going to look into the Hornady case length/head space gauge. I've never needed one before, but I think I definitely need one now.

 

[X-fan]

Forget the crimp...I shoot rifles up to 416 Rigby without a crimp.

Ejector marks mean the load is too hot. If this load has been fired 6 times why do I only see 1-2 ejector marks? Did you change bullets or perhaps another component with this load?

As the others suggested I suspect you are over-sizing your brass

 

[JeffinTX]

Sizing with either a full-length or small base die you only want to push shoulders back about .002".

.003" and more and your case walls will start to stretch and thin on each firing.

Some will say small base sizing is abusing your brass. Pushing the shoulders back .003 or more may be more abusive as the walls thin, contributing to shorter case life.

Thinning from pushing the shoulders back too far:

These cases were deliberately set back .003 to .005 to document stretching and thinning to failure:

Thank you for this post. Excellent objective data!

 

[Deadshot2]

Ejector marks mean the load is too hot.

OR:

There is excessive headspace and the case head is impacting the bolt face rather violently. Yes, hot loads can cause that but then you usually have difficult bolt opening and an accompanying cratering of the primers. The pictures only show a normal cratering for a Remington due to the chamfer they put on the firing pin hole.

 

[9H_Cracka]

OR:

There is excessive headspace and the case head is impacting the bolt face rather violently. Yes, hot loads can cause that but then you usually have difficult bolt opening and an accompanying cratering of the primers. The pictures only show a normal cratering for a Remington due to the chamfer they put on the firing pin hole.

Typically if this is the cause then the primer will actually flow past the primer pocket in its diameter. His pics show them inside the edge of the primer pocket.

 

[BuzzBoss915]

I hope there is no need for a remedial course in resizing? No offense, but really, just barely bumping the shoulder on a bolt gun is sufficient, and anything more than that is detrimental to case life.

Some of the posts might indicate that after six reloads, you have to expect case head separation. That notion is wrong. I always get more than ten reloads from my brass, although (admittedly) I stay away from Federal.

It goes without saying that benchrest people can reload a case more than twenty times, so a specific number of reloads, (6) will not end the usable case life. And, case head separation is not a normal way of retiring old cases, typically you get either enlarged primer pockets or split necks.

If this problem is incorrect resizing OR a headspace problem, you really need to get yourself the Hornady headspace gauge and understand how to use it. BB

 

[Land308]

The 1st time i had a case head separation it was due to excessive headspace. Get it to a gunsmith and have them through a no go gauge in there and check it. It takes less than a minute to check headspace and at least you can rule that one out. My rifle had "grown" some headspace. It started randomly blowing primers with a load I had shot over 3000 rounds of in that rifle then I had a case head separation and half the case stuck in the chamber.

 

[FLIGHT762]

I came in late to the discussion, but as to your question- "What did I do wrong? (Case failure.)". You failed to properly measure your fired cases for shoulder length and didn't set your F/L die to only slightly bump the shoulder .001"-.002". Unless you have a gauge, you are only guessing. You can go the old traditional way of smoking or marking your fired cases and slowly use your cases as a gauge in your rifle to slightly bump your cases shoulders when you F/L resize and set your die. It does work. I find it simpler with a gauge that will show numbers,

With some kind of gauge, you can see the numbers. A Mo gauge, RCBS precision mic, Hornady head space bump gauge, Sinclair bump gauge, Innovative Technologies headspace tool or the new Forster headspace bump tool all will give you the bump length in .001". The drop in gauges like the Wilson / Dillon types give a rough showing of the shoulder bumping, but they are not precise.

I feel when you decide to get into reloading for a precision rifle, it's a good idea to be able to accurately measure your F/L shoulder bump. When I first purchased my Stoney Point (now marketed by Hornady) shoulder bump gauge, it was like a light bulb lit up. with my calipers, I could see that at a certain number, my F/L sized cases would not chamber and anything under that number, cases would chamber. Not rocket science. It all started to make sense.

As far as neck only (N/O) sizing, I've found through having to beat the bolt handle open a few times at the range, I will only N/O 3, maybe 4 times in a bolt gun and then F/L size. Even if you F/L size every time, your cases with minimal bumping, you should get 10 or more loadings as long as you don't stretch the primer pockets out.

 

[damoncali]

Spring for an RCBS precision mic. You're probably just oversizing a bit. 6 firings is on the short side, but then again you're using a factory rifle. You can get more (sometimes a LOT more) out of a custom chamber and very careful sizing.

 

[1idCat]

Here is a little trick an old-timer showed me a while back.

For .308 Win/.243 Win cases, the datum line is .400" in diameter, which coincidentally is the diameter of a .40 S&W.

If you take a deprimed, empty .40 S&W case and put it on the shoulder of a .308 case, and measure the overall length of the two together, you can use the .40 case to accomplish the same thing as the Hornady headspace gage.

I use a Wolf boxer primed 40 S&W case because the steel case is less likely to stretch. Deprime and size the case for consistency. The exact diameter is not critical as long as you're not comparing with other sources.

You can also use a 9mm case to gage .223. The datum diameter isn't correct (.330" vs. .355") but still useful.

Try it!

If someone has a Hornady gage, try it and compare the results.

 

[Hookturnr]

Just one point to add, once you get the hornady headspace gauge so you can accurately measure to the datum point, get yourself a set of redding competition shellholders so you can set your die to resize properly and have full ram contact with the bottom of the die. This will make for MUCH more consistent resizing.