I'm not real familiar with factory loads because I never use them. However, I've been noticing something recently that I want to open up for discussion.

At our range, I've been lucky enough to find some spent, factory loaded brass that was discarded by someone who obviously doesn't reload. It was all brand new brass, so I took it to reload for myself (some 22-250, 7mm Rem Mag, and 300 Win Mag). Anyway, all of these cases had the primers completely flatened from excess pressure. Now, does that make sense? We as reloaders are always warned about watching for pressure signs, but the factory ammo that should work safely in all weapons seems to ignore this rule. You would think they would err on the safe side condsidering that every gun should be able to use their ammo. It just surprises me in these days of bolt and trigger locks, lawyers and gun activists that they push the edge with their loads.

Don't get me wrong, I love speed and usually load to get the best speed/accuracy combination, but I do it safely and in line with what the gun will handle (since they are all different). Just wanted to throw this out there and hear what you guys thought.

Jethro,

I wonder if they had left the rounds in the hot sun or in the car where the heat rose a lot higher than in the open air before they shot them?? This could cause such signs of the primers being flattened? Just a guess.

muskrat
live free or die!

I was sighting in a BRNO in the OMO camp (SW Ethiopia) a few years back. I was using Remington factory ammo. It's always hot in the Omo Valley. I noticed the primers were flat and actually had one rupture. Still that's what I had to I shot a nice Northern Grants Gazelle with the stuff.

Rich Elliott

Be careful watching primers for signs of high pressure. Some brands of primers use thinner or softer metal for the cups.
Also as was already said, leaving ammo in direct sunlight or locked up in a car can heat up the ammo leading to excessive pressure.
muck

The factory ammo is always right up there as far as pressure and velocity and safe to shoot in all guns. The reason the factory can do this is they are ALWAYS using NEW brass. You can load to the factory pressure and velocity, but the brass will only last 2 or 3 firing. Sometimes the powder the factory loads the ammo with is not available to the public. Primers metal is all said to be the same hardness, the primer mix is what makes a primer more sensitive (i just read that, i dont believe it to be true, but they are the experts)

About three or four years ago I shot a box of Winchester balistic tips in my Browning Eclipse 270. I believe they were 130 grn and although I don't remember the exact name they were the nickle plated cases. On two of them the primers fell out when I ejected the shell. I don't remember if the bolt was hard to lift or not. I was not handloading at that time and didn't really know just how significant something like that was.

After talking to some friends who told me this could have been a problem and I never bought another box of factory ammo again.

I can't count the # of factory ammo cases I have had split.Many different guns,years and Brands.
It happens. jerryboy

I've never considered flat primers a very reliable pressure indicator. As an example, I have some factory .416 Rigby cases, keep in mind these are loaded at 2370 fps, and can be safely loaded to 2650 fps that don't look a bit different than my .220 AI cases that are going 4100, and have .001 case head expansion. I know there is probably 20000 psi difference in these two- primers look the same.

There are several goings on that can cause a flattened appearance to primers other than high pressure.

With factory loads in factory chambers , it's likely sloppy headspace more than anything else .........

I tend to agree with Sdgunslinger. What I usually have found is excess headspace. the primer gets pushed back and flattened then the case stretches and "re-seats" it. I'll bet if you check the brass length it will be well over the unfired length. I have had more than one factory rifle that would stretch brass beyond max length every time it was fired; (as it came from the factory). This is a leading cause of case head failures. The reloader trims the brass fearing long necks crimping the bullet. Then if he full length resises; he shoots again and has to immediately trim again. Now the brass just off the head is getting really stretched thin. If you reload ammo for factory rifles; watch out for this.

jethro, how do you know for sure it was excess pressure that caused those primers to be flat??? There are a number of things that can cause primers to flatten besides excess pressure, you know! In addition, primer flattening is the least reliable method of determining that your pressures are too high!!

That said, factory ammo has been known to be overloaded a few times, as proven by periodic ammo recalls!!

I guess I should have worded my original post a little more carefully to say "from possible excess pressure". I had no way to know for sure if it was excess pressure, but seemed somewhat likely considering they were different calibers and brass manufacturers. What are the odds? The "sloppy headspace" explanation makes more sense. Is this problem that prominent among factory guns?

Jethro, it's not a problem! The rifle goes "bang", the brass is elastic enough to stretch, the primer holds, and the case extracts easily.

No one even notices it, unless they are an "enthusiast" like us reloaders. JMO, Dutch.

Virtually any factory chambers using factory loads will exhibit flattened primers due to the overly-generous headspace that big chambers and small ammunition results in.

Factory loads exhibiting excessive pressure are rare, but mistakes happen. Factories do tend to use faster-than-optimum powders because they can use less, which equals less cost. Faster powders with more air space tend to result in less consistent pressures and velocities, but the factories usually underload to the point that it is rare for the highest pressure individual cartridges to be so high as to be problematic.

The exception to this is the current high pressure loadings of the WSM series in an attempt to match the unrealistic marketing department claims for them. Within a year or two, the manufacturers will quietly back off on the WSM pressures and the "magic" and mystique will be gone from the short-fat line. As of right now, it is not uncommon to find individual rounds in the WSM chamberings that exceed normal pressure standards.

Have had a couple of boxes of cci /speer lawman ammo that was loaded on the hot side, cratered primers, excessive expansion and so on. It's always been the 9mm too, can't figure out why though. I have just stopped buying it altogether.

It really sounds more like a headspacing issue than anything else to me. I had a Winchester 88 .243 that always flattened and usually punctured factory primers due to a generous headspace, weak firing pin and short throat(ones that didn't puncture extruded into the firing pin hole). This only happened with 100 grain factory loads - lighter bullets didn't do it.

Even starting loads with 100 Grain pills showed excessive pressure when I attempted handloads and accuracy was never good with them either.

I relegated the gun to bench and groundhog duties only with 70 Grain MatchKings, and primer appearance and head expansion were fine, even with maximum loads of 4831. I also limited my resizing to just short of the case shoulder. The end results were no punctured or extruded primers, elimination of ejector marks, and excellent accuracy (3/8 - 1/2 MOA).

It just shows that every rifle is an individual and some combinations don't work well.

IMNSHO flattened primers are not reliable indications of excess pressure. loosened primer pockets, blown primers and seperated heads definitely indicate high pressure.

Brass is just too cheap (at any price) not too use new unfired brass from a reliable source. Depending on how much I plan to shoot a rifle, the caliber, and quality of brass I purchase 200 to 500 new cases of the same lot.

Wally