Home Forums Reloading Big Game Rifles Blew my first primer ever😳

My situation was a result of no believing my own eyes when looking at the brass before the blown primer. A clear ejector mark was on the case before theown primer. Each charge went up 1/2 grain in Imr 4350. The velocity I was chasing was actually for a Nosler ballistic tip 120 gr, rather than the Barnes tsx I was shooting. Sooo many lessons I learned the hard way. And sadly, I already knew them and still violated my own observations.

It happened to me once.
Cartridge was a 5.6x57RWS loaded with Norma 204 and a 62gr TTSX.
The load was extrapolated from a well known load with the same powder and Sierra 65gr GK.
First shot gave me an abnormally high velocity reading, but not observing any pressure signs (RWS 5.6x57 is extremely thick) I fired a second shot with the same results and the two impacts touching together.
Those were my Chrony days so I went to the chronograph, changed its set up a little in case it was a bit canted, adjusted the shade screens a tad and fired a third shot.
And ... well, the rest you know.

I never push my reloads to max as I dont see the point, I reload for best accuracy and I seldom get that by increasing pressure/max velocity....Im glad your OK and a good lesson learned cheaply....👍....Hb

I’m sure I’ve read somewhere that not all load manual data is actually pressure tested. I’ve read that some data is predicted from Quickload and then published. That would be concerning because I’ve also read that actual pressure testing and Quickload pressure predictions don’t always align.
I always try and use a few different load manuals/sources to figure out what a reasonable (sort of average) max velocity will be with a bullet/powder combo and my barrel length. Then use that as my max velocity regardless of powder charge.
I’ll stop before that chosen max velocity if I get a great load, or if anything sketchy happens.

So far I haven’t had any high pressure events when I stay within that max velocity.

The brass is already flowing at that point. A lot of handloaders then further make qualitative judgements on how “bad” it is, like the bolts stiffness, or elector marks are “not that bad”.

There is another issue that can cause severe pressure spikes that isnt associated with the loading process.
Its a thing called (case weld.)
It can happen with reloaded ammo that has been sitting for a long spell, like a few years.
The bullet actually attaches itself the the neck of the case, and can cause considerable pressure increases when fired.
Best solution before firing any old ammo, especially having larger cases, is to turn in the seating depth on your die and reseat the bullets a bit deeper in the case.
Listen carefully as you do it and you might hear what sounds like the cracking of a stick being broken.
Dosent seem to happen with new ammo or new cases, only ones that have been reloaded, even after cleaning the inside of the necks.

I've blown primers, at least twice based on my notes. When I was working up a 120 grain Nosler Ballistic Tip load for my 6.5x55 Swede I believe I was using data from the Nosler 6 book. My notes show that I started at 46.5 grains of AA3100 and started getting ejector flow marks right away at 47 grains. Stupidly, I blamed it on soft Federal brass and pressed on. The flow marks continued until at 50 grains a primer was cratered and at 50.5 the primer blew loose. Finally I stopped. That experience was within the first 200 rounds of shooting and handloading for my first centerfire rifle, which was intended as an Antelope gun when I lived in Arizona. That was 2008 and a year later I got drawn for a premiere Bull Elk hunt. I got a box of 160 grain Woodleighs Weldcore Protected Points and started working up what was going to be my Elk load with AA3100. My notes show that I started at 41.4 grains and by 41.9 grains they felt too hot. Maybe I was experiencing difficult extraction or just heavier than normal recoil, I can't remember. I continued and at 42.9 grains I stopped. According to my notes the Alliant data I had used had a starting load of 41.4 grains and that was supposed to produce 2155 fps. I was getting 2492+ fps. I blew the primer when I fired a single load with 42.9 grains of the AA3100. It looks like I was planning to back off to 38.3 grains which should have produced 2200 fps according to some Sierra data I had but instead I switched to VV N160 and settled on a final load of 39.5 grains of that with the Weldcores and that's what I ended up hunting with (intending to keep my shots inside of 200 yards).

I was younger and inexperienced with handloading and rifles in general back then. I never really intended on my Swede being pressed into service as an Elk gun because I always thought I would rather want to bow hunt Elk. When I got that tag I started thinking about all the moose and elk that have fallen to the Swede and figured I could really press those 160 grain bullets hard and increase my chance of filling my tag. In hindsight, I wish I would have just bought a 7 Mag and spent the summer learning how to shoot it with safe loads instead of trying to wring the max power out of the Swede with my limited experience. I think most of the data I was using then was for 160 grain Hornady bullets too. I believe that the .264" Woodleighs I had were really designed with the .264 Win Mag in mind. I probably would have been better off loading some 140 grain Partitions in the Swede at sane velocities. I eventually worked up a very accurate load with 130 grain Nosler Accubonds and 48 grains of VV N560 for 2750 fps and sub-MOA accuracy. That was to be my general purpose Mulie/Antelope load in the Swede when I decided to move back to Michigan in 2010. Now I am loading 46.6 grains of VV N160 with the 130 grain NAB's for 2843 fps, no pressure issues and very good accuracy. And that is now my Whitetail load for Northern Michigan hunting.

I hate to admit such bad practices and I certainly don't encourage them. But I wanted to share that so you know you aren't the only one and I'm probably worse than you!

I did eventually switch from Federal to Lapua cases and that's all I use now. I don't ever push the envelope anymore, I realize now that if you really feel the need for speed and you are seeing signs of over-pressure it's better just to step up to another caliber or chambering where you can achieve your velocity/energy goals with safe and sane loads.

One technique I use now that I haven't seen mentioned yet in addition to chronographing loads as I work up and looking for traditional signs of over-pressure is I mic out the case-head area just ahead of the rim before and after firing. If there is more than .0005" expansion I take that as a sign to stop. I got that from Randy Selby's video @therealgunsmith on youtube and I think he attributed learning that technique from Vernon Speer.

Measuring case-head expansion is one of the least accurate ways to pressure-guess--mostly because various brands of cases can vary considerably in thickness and hardness.

Vernon Speer used it because while he bought a copper-crushed pressure device for the company pretty early on, apparently nobody at the plant could use it consistently. Having visited Lewiston in summer, and seen parts of the old plant, I would guess this might have been due to trying to measure pressures at different temperatures--which vary a LOT in Lewiston. But using case-head expansion was also why the early Speer manuals listed pretty hot loads.

Today SAAMI has very defined pressure-testing protocols, including a consistent temperature.

Take his stuff with a grain of salt. In one of his videos he was making loading decisions based on SD from three shot samples. He may as well have been reading chicken bones.

As usual correct and very concise. 👍



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Some 6mm rifles shoot great when pushed to the max. And so far pushing .308 cal rifles hard has been a waste of powder for me. The one thing that I've found consistently is when you increase COL or temperature you increase pressure.

Many years ago had a load worked up in the winter for my 300 WM with Sierra 165 HPBt it was pretty close to max, took it out in July again and had blown primers, was scratching my head until I realized that 100 degree temp raised the pressure considerably. Now days I don't push the velocity as much, once I achieve good accuracy I stop.

And then there are folks like me.. who does a lot of load development work, with pistol and shotgun powder in low recoil rifle loads. I share the info on line, and so I work up my loads to the point, that I know where blowing primers will be found, and then consult my data, to list max at a point that is consecutively safe.

Even using load manuals, on the same page, I've had loads that I am blowing primers 2 to 5 grains below what is listed as max, then use another powder on the same page and same bullet weight, and can exceed the manuals max load by 2 to 5 grains before blowing primers or have loosened prime pockets.

What this has taught me is that each rifle and chamber is an entity unto itself. And load manuals are a reference, NOT a BIBLE of loading data. One needs to work up. Its your head, so choose wisely on what you're going to follow. Something blowing up in your face, can be hazardous to your health.

What Mule deer said. Use a chrono. Be careful mixing and matching data. Bullet makers data may or may not be pressure tested according to my source in one of the big companies. Powder company data usually is. This is why hogdon data is usually lower than say nosler data.

Good to hear somebody else bringing this phenomena up cause it’s really worth remembering. I didn’t see YOBUCK’s earlier post so forgive me but I’m only trying to add to your advice as I posted on this subject later. Anyway it’s not BS but a metallurgical fact and Frank Snow, who started Sierra Bullets in Whittier, CA. proved to me with a Hollywood press fitted with an inch pound gauge on the press. Old ammo can create a molecular bond between bullet and case neck. Not all bullets and cases can create this condition but if you have hot loads, or shooting P-dogs in the heat it’s sound advice to bump the bullets to break the bond. According to Mr. Snow this bond can actually require nearly enough pressure as a cannelure crimp to break which everyone should know is a very serious pressure component.

Rick

IIRC (!) common advice in loading manuals is to stop adding powder when you reach the max load OR max velocity.

Had one vanish on me with a .257 once. Made an impression, even though there was no other sign of trouble from the FN it was fired from. Been a good boy ever since!