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Reading your primer...the poor mans pressure guage...

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Reading your primer


The primer can be your view into the soul of a load. Since most of us don’t have the special instruments to check the pressures of our loads the primer becomes our pressure gauge.


When a cartridge is fired the pressure builds and the bullet gets pushed out of the case, down the barrel and away. The same forces that operate on the bullet are also forcing their way back and to the only other movable part of the round.


Smokeless gunpowder doesn’t just go BOOOM and its done. That isn’t how it works. It burns at a specific rate and each powder is different. As it burns it creates gas that is expanding. As the pressure builds the powder burns faster and as it burns faster the pressure builds faster. This building pressure is what makes a bullet go.


In general the longer the barrel, up to the point where all the powder is burned, the faster the bullet will go. Factory loads are designed for the average barrel length and for use under average conditions when fired from average weapons.


Reloading allows you to tailor a load to your specific weapon. You always start at the low end of a load. You use the bullet, the primer and the powder that is specified but back off the top load and then work up to it carefully.


I usually load in 10 round batches. This is enough to give it a good test and not too many if I have to pull the bullet and scrap that load. I first fire just one round and then based on the recoil and sounds I may pull the case out and look at it.


The primer will tell you what is going on. If the primer still has rounded corners and the dent is just in a flat smooth primer you are still well within its comfortable operating pressure. Fire the rest of the rounds and check the primers on each. If they stay the same and all look about the same you can weigh out a little heavier load of powder and do this again. I usually carry a bout 5 or 6 batches with me to the range starting with the lightest and moving up a little at a time.


You will notice that as the pressures go up the primer will start pushing back and the corners will start to square off. If you keep going the primer will get totally flat with no rounding to the edges.


The next thing you will see as the pressures rise is that the primer will start to extrude. This means that it is fire forming to match the plate that the firing pin goes through. This is about as far as you want to sanely go generally.


If you go past this point the porimer will start to extrude out and around the firing pin. It will look like a moon crater with the edges rising up above the level of the pocket.


The next thing you will see will be either a primer that is pierced and allowed an escape of gasses or black stains where gas escaped around the edges of the primer. At this point you are way past any level of safety.


When the extrusion gets even more extreme it will extrude back and into the gap around the firing pin to the point that it will lock a revolver up and in the final stage the base of the case will budge and the primer will blow completely out. This is a MESS and dangerous as hell. You are right on the edge of maybe blowing the gun!!


I’ve never blown a cylinder out or a barrel up but I’ve had the primers just fall out of the case when I finally got the cylinder open and the case out. That mess up scare the crapola out of me and I used the rest of that powder for fires and such and never used it again. It was Winchester 296 and they tell you in the loading manual to NEVER vary from the specific loads that the recommend. They are SERIOUS!!


My first round shot great. These were HOT maximum loads that I was using for silhouette shooting. The Rams at 300yards are actually a bit much for a 357 mag so I was pushing hard.


I finally figured out what went wrong and caused the problem. There was a mix up and instead of using once fired of brand new cases for the load I somehow got a few older cases. They were longer than they should have been and so the crimp die that was set for new or once fired cases had put a massively heavy crimp on the bullet! This heavy crimp delayed the bullet release for a nanosecond and in that moment the pressures went through the roof.


I discovered this when I started pulling the bullets out of the rest of that batch. Little things CAN make a huge difference when you are out there on the edge. The loads when they were right were high pressure and there was just the beginning of a little pitting and extrusion around the firing pin. The heavy crimp pushed it right off the edge! Thankfully It was a Ruger Blackhawk and it handled the pressure without damage or injury to me. That said I had to pull the pin and knock the cylinder out with a nylon hammer. The case had to be pressed out of the cylinder too.


Watch your primer and as you see the pressures going up you need to become ever more careful and uniform in your specific actions. When I’m up there I weigh every load to perfection and then put the bullet in immediately.


I’ve probably loaded several hundred thousand rounds and that is my only BIG mess up. When I was feeding several 5.56 autos, we loaded a thousand at a time. I always bought my bullets by the pound from a wholesaler. Her would have wooden barrels with 357, 9mm, 45, 223, 7.62 bullets and you just scooped what you wanted into a box and paid by the pound. GOOD DAYS! He sold powder in bulk too. Like me he was put out of business by Janet Reno’s goons.


Oh, as always all of this is just in my humble opinion and since I’m a crazy sucker you use this and all info at your own risk…LOL

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Looking for some new venue and I found this Damn is right about primers in rifle and pistol I would add a note


this does not work in shotguns by the time you get a "SIGN" it may be way to late so you need to pay attention to


posted load data.


unless we go into TEOTWAWKI stick with pposted information and not go rouge until your left with no options.


The data is general suited for powder charge and charge / shot weight components are a variable primers can be


more powerful than another but begining with stating loads and staying under max you should be fine.

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When using  primers, I always mnake sure that I load the primers for the inteneded cartridges by hand, AWAY from the reloading bench and anything else that could cause any kind of sympathetic/spontaneous combustion/detonation.(just a safety thing with me)

the slowest part of all my reloading IS inserting the primers, as I don't like to waste them, I'm extremely careful about putting them back into the fully cleaned (and reamed if necessary) primer pockets. never had any issues with blown/extruded primers or FTFs either, with MY personal reloads.(knocking on wood)

I have specific loads that include specific powder charges, bullet weights/types, and primers. I'm boring, I don't deviate from that, another safety thing with me. I like my loads accurate and they are.

As a rookie reloader, I did double-charge a few cases by trying to load far more cartridges in a single session than I should have. I now limit myself to no more than 200 (progressive press) period.

On my single stage press, it's 50 tops, that's used for most of my longer range rifle cartridges.

Also, I have consolidated calibers, so that I'm not having to store or acquire lots of different calibers of bullets, cases, powders and primers for different jobs, that didn't make CENTS at all. Now, the economy firmly on the downward spiral into the toilet, it's only going to get worse.

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very good safety instruction TPSnodgrass


when  I was a kid we got a few primers and laid them on a concrete slab and hit them with a hammer BAD VERY BAD idea


first they were loud as hell second and we did not know it at the time the hammer was heavy enough to keep the splatter of


metal from flying up but it did not keep it from flying out and we had splinters of the brass and concrete grit stuck in the skin of our legs


and I know a boy that popped a 50 cal primer to decommission a shell and he has a permanent pock mark on his cheek 


where is stuck in the skin as well as burned it We could have been blinded by concrete or a sliver of brass just as easy.


I use a tray hand primer I wear safety glasses and a do not put in a full 100 into it and I abide fairly close to your safety measures


A friends father was priming a bunch of shells and had a whole carton of 1,000 primers in a small glass pickle jar one popped in the press


they ones left in the jar exploded and blew off 3 fingers and perforated his wrist and arm we called him the claw because that is what his


hand looked like a thumb and a finger and a nub of his middle finger.


I used to process tons of brass from ranges the powder swept from the floor was also dumped into the barrels paper shredded by bullets


passing through the targets and unburnt powder this would go through the sieve and I would collect it and put it on a burn pile for leaves and


yard litter I had been doing it for weeks it ha even rained a few times I had about 3 to 5 pounds of this stuff and enough small limbs piled up


a friend came over and was smoking he threw the still lit butt into the burn pile and whoosh I sh8t you not it looked like the finger of God


from a Cecil B. Demille film it was a column of blue with a green tip orange at the base about 20 or 30 foot high and burned for many seconds.


scared the sh*t out of all of us and it was round the diameter of the pile more or less that was one eerie sight from then on I would 


burn the powder every day and would not let it build up in the trash bucket in fact I traded out our plastic buckets for metal.


I like you TPSnodgrass feel it is questionable if things will back to pre 2012 stock on the shelves and or "OUT OF STOCK"


next to everything on the page specialty companies make their own bullet and have their own machinery others have their stock made


by others with their design of bullet I have noticed that Berger and Nosler as well as some others have bullets at much higher prices


as well as higher shipping costs unless you buy enough to offset the postal costs one box of bullets can end up costing almost 30 bucks


to 60 dollars and some now come in boxes of 50 instead of 100 I am waiting on the 20 pack.


yes there are powder and primers out there but finding them is hit and miss I have seen in stock and the next morning out.


I think a bullet mold and a keg of powder and a case of primers is better than a 401K as far as future investment.

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I just reread this post. All excellent safety ideas! I wonder sometimes how we survived when we were kids. Hell I remember playing a sort of spin the bottle with 22 shells and hammers. LOL, I was the smart one and understood that it was the case that would nail you and not the bullet.


On the reading of primes post I made earlier... Snake is right and this only works for metallic cartridges and not for shotgun shell reloading. I want to also add that this sort of thing is also NOT for loading for semiautomatic weapons of any sort. Long before you might blow a primer you may just totally mess up your gun!! Automatics are designed to work at very specific pressures and either more or less can make them malfunction or be damaged. I was reading primers only on revolvers and breach action pistols; bolt action, leaver-action, pump and single shot rifles. MOSTLY bolt and single shot because leavers and pumps are not generally as well locked as bolts and singles.

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