308 coal and pressure

W

wjarrell

New member
Ok I have a question and a problem. A little back ground first. I'm brand new to reloading, I use my buddies reloading equipment. I'm shooting 308 168 grain Berger classic hunter with 44 grains of varget, new Winchester brass, and Winchester primer. My old coal was 2.800 with once fired brass, same components. Now.... I reloaded a batch last night with new brass that was sized and trimmed and later found out that my new reloads measured 2.810.

Never had preassure signs with once fired brass and coal of 2.800. Now I have pressure signs with new brass and coal of 2.810, put a pin hole in the bottom of my casing. Now what do you think is causing the pressure signs?
 
Is this the same lot of Varget or from a different jug / container?

What kind of rifle is it?

Do you by chance know how far from the lands the bullet is seated when loaded to 2.800?

If the bullet is seated right at the lands when loaded to 2.800 it is possible that another 10 thousands would result in a rise in pressure, however I would say this seems an unlikely scenario.

2.800 is a standard length so the odds of your rifle being throated so that 2.810 would result in a jam seems unlikely.

Are you sure you loaded the same amount of powder as the previous loads? What kind of scale are you using?
 
The short answer is pressure. The question is why? Your load is below the maximum listed by Hodgdon for either a standard 168 grain bullet or for a Barnes solid, and they develop their loads in Winchester cases. The only difference is, they use the Federal 210M primer, which is slightly milder, though the Winchester is by no means a hot primer. This shouldn't happen.

Where was the hole exactly? Pinholes in primers are not uncommon, but in the bottom of a case head they are pretty much unheard of. It would take a defect in the case to allow that. If you have that, I would contact Winchester about it. Their cases are more generous in capacity than the once-fired military brass, so pressure in them, with a given load, actually tends to be lower.

Now, if it is actually the primer that pierced, my first question is whether it is one of Winchester's brass colored ones? Compared even to the Federal (a soft primer) the unplated Winchesters are soft and pierce more easily. So if this is the case, I suspect the primer and changing to a Federal or other heavier primer may well solve the problem.

The 0.010" additional COL isn't much. It's due to how springy the brass is. Indeed, if you look at the SAAMI drawing, 2.810" is the maximum length for the cartridge. What I can't tell from that number is how far off the lands your bullet is. It always depends on the bullet shape, though Berger doesn't normally make bullets with a short ogive radius, so I'd be surprised if it was getting too close to the lands. If it did, that will raise pressure.

One of the differences between Winchester brass and some others is that it uses a semi-balloon head. Look down inside and you can see the brass around the flash hole is a little mound. This means the brass around that mound is thinner than on other cases, so it would theoretically take less pressure to pierce. However, the head was designed that way to increase powder capacity, not to lower pressure tolerance. So, again, it shouldn't pierce without a defect being present.
 
My old coal was 2.800 with once fired brass, same components. Now.... I reloaded a batch last night with new brass that was sized and trimmed and later found out that my new reloads measured 2.810.
Click to expand...

.010" difference in length when measuring COL? I can manage more difference in length when measuring the OAL of cases without changing anything.

then there is 'that hole':

put a pin hole in the bottom of my casing.
Click to expand...

Putting a hole in the case head is scary, then there is the primer and or around the primer. Anytime a hole appears in the primer there is going to be gas cutting. And, there are different kinds of holes.

And there is a difference when comparing once fired and new/unfired cases. It is something like annealing, there are rules, for me rules are simple.

F. Guffey
 
Here are some pictures. My rifle is a Remington Model 7. I fired 14 rounds and this was the last round that I fired. Only two of the previous rounds showed a very slight pressure mark. This is a different lot of varget than my last batch of reloads. Powder dispenser is a Lyman 1200 dps3. My buddy thinks its a bad case.
image_zpsd44d5xq7.jpg

image_zpsfgz5oqpp.jpg
 
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That's a pierced primer cup at its outer edge. It occurred because the primer flattened and the edge squared up and got too sharp (over-bent). I think you'll find that goes away either if you move to a primer with a less weak cup, or when you use the same brass a second time.

The fact this didn't happen with the other brass is most likely because the once-fired brass, having been previously expanded to a greater length, had enough spring that your sizing die didn't make it as short from head to shoulder as your new brass is. This meant the new brass had more head clearance in the chamber when was fired, so the primer backed out farther and inflated more (mushroomed) at the bottom of the cup during the initial pressure buildup. It then flattened to have that sharper and more frail corner formed when pressure got high enough to stretch the brass back against the breech face (which is what reseats the protruding primer).

If you have a means to measure the head-to-shoulder length (improvised method is shown below), then unless this rifle is a self-loader, just turn the seating die down far enough to make the case one to three thousandths shorter than it is as it comes out of in your chamber, but before resizing. I expect the greater primer flattening and pierced corners will then go away. For the rest of your new brass, though, I'd recommend using a primer with a stronger cup. Try CCI 200 for strength. Try Federal 210M for consistency. If the powder charge doesn't fill the case well, a magnum primer (CCI 250 or Federal 215M) may give you better velocity consistency and will definitely be tougher than a standard Winchester. You will, however, want to drop the charge weight at least 5% and work back up if you go magnum. It often has no effect on peak pressure, but sometimes it does, so this is a reasonable precaution.

poormancomparator_zps061e19f7.jpg


PS, I edited your post to change the [url]…[/url] tags to [img]…[/img]. If you do that, you will get them to show up directly, as they do now.
 
Looks like pretty high pressure to me. Is that an ejector smear I see?
FWIW Regardless of new or old brass OAL has nothing to do with the brass. In addition 0.01" difference in nose profile is not unheard of.
 
Mobuck, pressure mark does show on that case, it did show on another case but it was very very lite. The first preassure marked case I found was my 8th shot and then the case in the picture was my 14th shot and after that I stopped shooting.
 
I guess my last question is what do I do now? Do I drop my powder charge? Should I change primers or brass or is this just a faulty primer?
 
Personally I would change primer, I use CCI and work your load up again checking for pressure. How is the flash hole and primer pocket on the one's that holed ? I'd maybe bin that brass with the marks to eliminate any weaknesses that could have happened to that 2 shells. Could just be the primers that failed maybe ? Bad batch ??
 
I sort cases by head stamp, once I acquired some magnificent cases, I sorted the cases into groups of 20 and loaded them. Not long after that I was informed there were mistakes in the manufacturing process. I moved the cases to the collector drawer, that put them next to the BM 1940 30/06 cases. I found nothing that would indicate there was a problem. The caution did not say the cases would blow up the rifle, it was suggested 'it could happen'.

I acquired more cases from an old friend, he had 40 of the suspect cases. My cases came form a metal recycling yard, he got his cases as issued. He fired the cases and then reloaded them, again, I thought the were magnificent cases.

F. Guffey
 
I haven't popped the primer out of that case yet but when I do I will report back. Along with trying CCI primers, should I try a different brand of brass too or stick with the same Winchester brass?
 
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