Something went wrong.....

[10wt308]

I am so glad you are OK!
I too shoot a 700 custom chamber and use 42 gr. IMR 4064.
Hope someone can tell you what happened. This event will make me re-evaluate my procedure. No body around, no TV (I may have a radio on very low for background noise),
Only one powder on bench at a time. Of course no alcohol or if I’m tired do it later.

Good luck and glad your good

[Bart B.]

#2 Gunsmith's theory: Primer was not fully seated and caused the case to be pushed farther into the lands and grooves while also having a weak primer seat. Overpressure took path of least resistance which was backwards. Also may have helped slam the case back into the bolt face. this was the last batch of cases I prepped with a reamer versus swaging so maybe? Also the last run of rifle round from my progressive press before moving to single stage so its possible it could have happened.

Regardless of how deep the primer is seated, the firing pin will fully seat the primer as it drives the case hard into the chamber shoulder.

If the case was resized to have .003” head clearance in the chamber, closing the bolt on such rounds will seat the primer such that it protrudes .003” past the case head with the case shoulder forward against the chamber shoulder.

Then the firing pin fully seats the primer a few thousandths more, the round fires and the case head gets pressed against the bolt face.

[J.G. Terry]

I had returned some pretty badly damaged Remington firearms for customers. The company, in that day, did right by the customer even if it was a reload. Starting with the simplest cause for a KB helps with the assessment. Simplest cause is an overcharge. Usually, an unseated primer causes a misfire.

[reynolds357]

I often wonder if sometimes its the bullet. In one of ny 1000 yd match rifles, I had something similar happen. My brass is meticulously prepped. My charges are weighed. There is no way to get enough of the powder I use in the case to go over pressure.I jam the bullet in the lands. No pressure signs on hundreds of that particular load. 2 rounds out of the last 100 shot very low and had to beat the bolt open with deadblow hammer. It had to be the bullet.

[Blindstitch]

If you don't want to wait for a bullet puller get a pair of visegrips, wrap some masking tape around the bullet and clamp on. This will let you break down a few cases to get some powder weights.

[Colorado Redneck]

Reynolds357
I had the same thought, maybe an oversized bullet. It would probably have to be a bastardized projectile, as the next biggest bullet would be .338, or .03" bigger in diameter. Maybe, just maybe the round would fire with .338 slug. Pressure would be off the chart. I have never ever checked diameter on bullets, just trusting the factory would never accidently mix in anything screwy.

[mehavey]

This is not a bullet-in-the-lands problem.
That's +10% pressure at most.

Barrel obstruction would have blown the barrel, not just blown the case.

Since you shot prior rounds from same loading lot, hardly likely it was wrong powder;
Primers look totally normal.

I'm thinking defective case/brass head failure -- entire/statistically plausible w/ military brass.
Once 60,000 psi gets loose at all, no matter how,... lotsa excitement.


.

[reynolds357]

Originally Posted by Colorado Redneck

Reynolds357
I had the same thought, maybe an oversized bullet. It would probably have to be a bastardized projectile, as the next biggest bullet would be .338, or .03" bigger in diameter. Maybe, just maybe the round would fire with .338 slug. Pressure would be off the chart. I have never ever checked diameter on bullets, just trusting the factory would never accidently mix in anything screwy.

I have got wrong bullets in boxes before. I got 4 in 100 once(that I noticed). They were wrong weight, not wrong dia.
In my case, It would have had to be an over weight bullet. I have a tight neck chamber, so there is no way I would get next diameter suzr up in the rifle.

[Don Fischer]

None of the primer's shown look flattened to me even a bit! Two thing's I might think 1) bullet touched the lands with a max load. If there were no pressure sign's I'd do the same max load. But if you were to close to the lands and got one bullet not quite seated all the way, you could have had it on the lands. Thing to do when loading close to the lands is not judge by feel so much as by sight. You touch the lands you might not feel it but you can see it on the bullet ogive. Scratch's on the bullet ogive will be caused by the lands! 2) you sure you got all the case's trimmed to under max length? If you missed one the mouth could have just got to the lands and not released the bullet right, bullet pinched in the case. I trim my case's and they are not all exactly the same so I only worry about them being under max length. Of course it could also be a bad powder chg, to heavy. Your working at or close to max, throw and weight every charge. Some of my rifle's will go over max in my manuals but I throw and weigh every single chg unless using ball powder. Keep in mind that even with heavy case's you can still possibly hit max chg's without going way over pressure and way over is what you have there. Each rifle is a law unto itself and you may or may not reach a max load that is in a manual no matter matter the case, bullet, powder or primer or even seating depth. The data in the manuals does not necessarily work in every rifle, that's why you get starting point to work from. Your job is to be able to load using safe procedure's and to be able to understand pressure signs. As the primer's photo's you posted, none showed any pressure! Also don't see any other pressure sign on the case, ie ejector mark. Most reliable sign for me is hard opening of the bolt! Any resistance to closing the bolt is to me a sign something is wrong, ie OLL to long or bullet seated touching the lands. Resistance could also be a case not resized enough and the case still rubbing on the shoulder. If that happen's and some guy's like that, it hides the bullet touching the lands! Your are welcoming a disaster.

As for the question, what caused this? Excessive pressure! Pure and simple. Learn to avoid the possibility of that. many people refuse to go near max loads feeling better accuracy comes at reduced accuracy. Might be a good idea for you till you figure out a few thing's. You obviously missed a pressure sign and if you think the photo's of primer' shows a flat primer due to pressure, you could not be more wrong!

I might add one last thing. Cycle every round through the chamber and look for something to tight before firing the rounds. That alone may have prevented this blow up! A suggestion for throwing powder, weigh light and trickle up. If you'll throw a charge and bump the measure handle a time or two before dumping stick powder, you will increase the weight of the chg and you'll only find that by weighting every load! DON"T bump and throw. Throe light and trickle up!

[T. O'Heir]

"...CCI #34 primers..." Those are not required. They are nothing more than magnum primers. Magnum primers might increase pressures in a regular case. The issue is there's no way of telling if or when the pressure might be excessive.
I kind of suspect(My WHAGs are Wild and Hairy.) the combination of milsurp cases, magnum primers and maybe how you put the powder in contributed to an over pressure load.
However, as mentioned, milsurp brass requires a 10% reduction of the Start load of 41.0. That'd be 36.9 for the Start load. Your 42.5 while just fine in commercial cases, is 5.6 over the start load. And, if one reduces the Hodgdon Max load by 10%, that is 40.9.
Hodgdon says Max of IMR4895 for a 168 is 45.4(C). Powder compression starts long before one gets even close to the Max. Manuals use commercial cases, not milsurp.
"...Primer was not fully seated and caused the case to be pushed farther into..." That's nonsense. If anything the bolt would push the primer in more.

[Pathfinder45]

Stick-powders have a tendency to bridge and hang up in the powder measure. That which hangs up in one throw can get added to the following throw. This could have been the case here if you haven't truly ruled it out.

When I load stick-powders, I weigh every charge and trickle to uniformity before it goes in the case. I also do this with ball powders whenever the load is near maximum; if not, I may choose to weigh every 5th or tenth round. But they all go in a loading block and the whole block gets a visual powder inspection in bright light to make sure they all look consistent before bullet seating begins.
So, obviously, I am loading with a single-stage, basic system with no automation. I'm not sure how y'all do it with your progressive rigs, but I'm thinking there may be some variations between all of you depending on the actual equipment, etc. But I will strongly suggest that if you are not weighing every charge as a separate operation, that you switch to ball-type/spherical propellants. Leave the extruded propellants for carefully measured accuracy loads done the slow way. Have you tried Hodgdon's BL-C(2) powder in your 308? It could be an excellent replacement.

I think the 2nd most likely cause could be that an incorrect bullet may have gotten into the pipeline, perhaps a 303 caliber?

[Unclenick]

Wisest.fool,

The first thing we need to establish is what you are loading. You listed a 168-grain ELD-X. Hornady does not appear to make one. They make a 168-grain ELD, and they make a 178-grain ELD-X, the lightest ELD-X shown in their line. So, if your bullet box says ELD-X, the bullet must weigh at least 178 grains. Please check and see which bullet it is.

Let's find out your actual case capacity. Take a fired case that has not been decapped or resized yet. Weigh it and measure its length. Fill it with water level with the case mouth (no meniscus, either positive or negative and no extra drops on the outside of the case) and weigh it again. Subtract the empty and dry weight from the wet weight. The result is what is called Case Water Overflow Capacity. That and the case length are what are needed for QuickLOAD. If you repeat that measurement on 30 cases and list them all, we can get a statistically very sound idea of what the variation in the capacity of those cases looks like to see how much chance of a case having extreme variation there is.

For everyone discussing them, the CCI #34 primers are identical to CCI 250 magnum primers except the anvil is shaped to be a little shorter and with wider-angled legs. That anvil design reduces their sensitivity to military levels to better tolerate the inertial impact of a floating firing pin on a primer cup. The cup is no harder than the CCI 250. I got that information straight from the horse's mouth by calling and speaking to CCI about it. The lady on the phone looked up the cup and the priming mix and priming mix quantity and confirmed the CCI #34 and 250 are identical in those regards and only the anvil is different. The only military sensitivity primer currently on the U.S. market that reduces commercial sensitivity by using a thicker cup is the Federal GM205MAR small rifle primer for the AR. Federal gave me that cup thickness information by email. Otherwise, that primer is the same as the GM205M standard match small rifle primer. They don't make a military sensitivity large rifle primer.

Too much primer? IMR 4895 does not need a magnum primer to ignite well, and, indeed, shooters often report the best accuracy with primers that are on the mild side. Palma Match brass from Lapua even has a small rifle primer pocket with a smaller-than-standard flash hole (0.069" instead of 0.079") to cut down on primer influence on final pressure and is intended for stick powders like N140 and 4895. The Remington 700 does not have a floating firing pin, nor do most people work a rifle bolt so fast that a floating firing pin would pick up the inertia needed to fire a cartridge even if it had one. For these reasons, there is no point in using military-sensitivity magnum primers in this load for that rifle and the hotter primer is possibly raising pressure unnecessarily. Add that to what is possibly an overweight bullet running a couple of grains of powder over its maximum, and you have elements to contribute to gaining some pressure.

That said, a case should withstand proof load pressures at least once. The top of the .308 Win proof load range is 92,000 psi. This expanded case head has gone well over that. If it were simply a case head flaw, you would not expect all that primer pocket expansion. It clearly tried to hold up to press that was grossly excessive. Hodgdon's data for a 168-grain Sierra MatchKing in a Winchester case (a couple of grains more room inside than LC) shows IMR 4895 loaded to 45.5 grains maximum and compressed about 2%. After tweaking QuickLOAD to match their pressures, it takes almost 51 grains of powder compressed about 15% (very difficult to actually load) to get to the top of the proof range. If I switch to assuming a maximally fast lot of 4895 I can reach the top of the proof range with about 48.3 grains and 9% compression, which is possible, though just barely. The above makes me doubt a simple overload is responsible, though if the bullets were 178-grain ELD-X types, the 168-grain proof load would get up to about 110,000 psi. But that takes 114% compression, and that's very hard to achieve.

Wrong powder? We seldom interrupt the flow of the loading process once we are setup and running. So unless you had to interrupt to use a different container of powder, that seems unlikely, but odd things happen. Occasionally someone will “return” a powder to the wrong container without realizing it. Letting someone else load one of your rounds could do it. Letting someone else’s load get mixed with yours could do it.

In any event, with the uncertainty, you are right to want to pull the rest of the bullets. IMHO, the best bullet puller for doing large numbers is the Hornady Cam-Lock Bullet Puller. It works with different collets for different bullet diameters and you would have to get their .308 collet separately to go with it. It takes a little setting up to get it adjusted, but once you do, it is way faster than the T-handle type collet pullers, much less the inertial pullers. I have pulled down thousands of surplus rounds with mine.

Did something get into the case? I once had a piece of Lake City 30-06 brass that felt odd in my hand. It turned out to weigh 35 grains more than other cases. My inspection found a lump of bullet core lead in the case down near the head and impressed against the brass by firing, so I had to get it out with a pick. Anything that can use up case capacity will raise pressure. An insect crawling in, if it hasn’t dried out, will take up space and raise pressure.

Was there a bore obstruction? If a bullet is fired into the bore and gets stuck, you experience essentially no recoil, which you ought to notice. The case doesn’t seal against the chamber well, so a little smoke comes out around the bolt. You still get some sound, but it feels wimpy. No bullet hole appears in the target. There are other kinds of obstructions left by cleaning tools. A broken Bore Snake; an unscrewed or broken cleaning rod jag and patch, etc.

Undercharge of powder? In Dr. Lloyd Brownell’s 1965 study of absolute pressure for DuPont, he finds charges of IMR powders (3031, specifically) at around 30 grains of charge weight in the 30-06 (about 55% case fill) begins to demonstrate very erratic pressure. This is at its worst at 25 grains (46% case fill). It appears to be due to charges that light being able to spread out in the case enough for more of it to ignite at once than occurs in a normal powder column burning from the breech end forward. Later, writing in Handloader Magazine in response to another writer opining that reduced charges of that sort were fine because he’d never had a problem with one, Dr. Brownell pointed out the issue is statistical in nature, meaning very high pressure excursions had a low occurrence probability, but it wasn’t zero as his lab had observed up to double the rated cartridge pressure occurring in this circumstance. It might only happen once in 20,000 rounds, but it can happen, and bad luck can make it happen the first time you try one.

Had powder gone bad? Many powders, when they start to break down, will consume their deterrents early on in the process, leaving the remaining powder burning much faster than it should, which raises pressure. The Navy documented roughly 50% pressure increases caused by this. I have seen powder breakdown in individual cartridges in a lot while others remained shootable (in the short term). This is randomly initiated when a group is near to going bad, and one of the cartridges has to be first. However, unless you have a bad lot of powder or have exposed the individual cartridges to excessive temperatures for some time period, it is another improbable cause of the problem. Just not impossible. Since some lots of some powders wind up recalled for premature breakdown, carefully inspect the powder in the cartridges you pull down. Make sure none is getting oily looking or clumpy. Make sure none has an acrid acid scent to it. Pour it on a sheet of white paper and slide it off, looking for rust-colored dust to be left behind.

I, too, would be concerned about cracks in the receiver lockup area. The idea of sending it to Remington is the best one. They will tell you if the receiver is salvageable or not. In the event there was a blockage in the receiver, you want them to look for a bulge in the bore, too.

[big al hunter]

.Reynolds357
I had the same thought, maybe an oversized bullet. It would probably have to be a bastardized projectile, as the next biggest bullet would be .338, or .03" bigger in diameter.

There are bullets available for 303 and 7.5mm rifles that are .311 dia. Better check the remaining bullets for diameter.

I can't get the pictures to show up on my phone to see what type of damage was done. To those that viewed the photos; are there signs of case failure due to prior stresses. Was there a week spot in the case that caused catastrophic failure. Incipient case head separation is warned about in all the manuals I have.

Did the cases come to you as loaded ammo, or "once fired".

[Unclenick]

No. He had a head blowout. I'll copy his photo to here for you to see. He got to very high pressure.

[greaseswabber]

Could this be a fatigue failure in the bolt? If the 42.5 gr load was always over pressure (lacking obvious pressure signs like very flat primers and difficult to open bolts) could what sounds like several hundred rounds apply enough incremental force to weaken the bolt and eventually cause it to fail? OP also mentioned that the two rounds before the final round loaded with more difficulty. Perhaps this was the bolt starting to fail.

[50 shooter]

It wasn't from a weak bolt, I think the case failed. Probably from being loaded a second, third or...? time.

It sucks but it does happen, OP is lucky that he wasn't hurt. Hopefully the factory will give what's left of his rifle the ok and he'll just have to replace a few parts.

[mehavey]

As before... given the sequence and repeatability in the same bullet lot, powder bottle, loading sequence and it not being an obstruction which would have blow the action/barrel...

Hard bolt closure is invariably a sizing issue, not bullet/lands engagement (and the camming action is hardly felt)
Nothing even close to 42.5gr/IMR4895 -- even using a 178gr AMAX -- will produce more than the low-mid 50's ksi (QL)

case head failure.

[reynolds357]

Originally Posted by mehavey

This is not a bullet-in-the-lands problem.
That's +10% pressure at most.

Barrel obstruction would have blown the barrel, not just blown the case.

Since you shot prior rounds from same loading lot, hardly likely it was wrong powder;
Primers look totally normal.

I'm thinking defective case/brass head failure -- entire/statistically plausible w/ military brass.
Once 60,000 psi gets loose at all, no matter how,... lotsa excitement.


.

Over the years, I have separated quite a few pcs of Wby brass at the belt and never had very much excitement.

[mehavey]

Brass separation (generally enclosed at least in part within the chamber walls) rarely causes that much excitement as compared to blowing the exposed head (outside those chamber walls).





BTW... are you fully sizing those Wthrby cases, or using a comparator to size just off the shoulder ?


.

[reynolds357]

Originally Posted by mehavey

Brass separation (generally enclosed at least in part within the chamber walls) rarely causes that much excitement as compared to blowing the exposed head (outside those chamber walls).





BTW... are you fully sizing those Wthrby cases, or using a comparator to size just off the shoulder ?


.

Most of this happened many, many years ago when I was full length sizing.

[mehavey]

Roger that.
I learned the hard way with the 375H&H & 300WinMag

[big al hunter]

Unclenick, thanks for posting the picture.

Now that I can see what happened....that was extremely high pressure. I would recommend checking every charge of powder as you pull the bullets from the remaining loads. If you see a large variation in powder weight, I would bet it was a detonation due to a very light charge. Check bullet weights and diameter as well. Let us know what you find out. And thanks for posting your experience. It is a good reminder of what can happen.

[David R]

I did that once. I was loading cast bullets in my Remington 700 VL with WW296. I was also loading jacketed with 748. I was actually chronographging my loads when the first one sprayed me in the face with powder. Chrono read 4,000 fps. I took the rifle home and used a block of wood and hammer to open the bolt . The bolt handle broke off. I sent the rifle to Remington. I sent a letter stating what I thought happened. I then pulled the bullets and weighed the charge and bullets. It was a 55 grain bullet with a Jacketed portion of WW 296. Once I figured that out, I wrote a letter to Remington explaining exactly what I had done. They fixed my rifle, new bolt and barrel for free and returned it to me.

Now there is only one can of powder in my reloading area.

David

[FrankenMauser]

This wasn't a case failure.
It was an EXTREME over-pressure event.

[David R]

A really hot load will blow the primer out. That blew the whole pocket and th bolt face.

David