|From: Gunrockets (Original Message)||Sent: 07/11/2005 18:48|
Exploding Primer Myths
I keep reading in the gun magazines old myths being repeated by supposible knowledgable gun writers. In magazines that are well respected. Such as Guns and Ammo and Guns and American Handgunner, even in the NRA's American Rifleman. So it is time to explode some of those myths.
Primer Myth # 1 This one I read today, and it surprised me that the writer did not know about internal ballistics and how primers are constructed. He stated that when loading small charges of fast burning powder in large volume cases such as 45 LC the primer could flash over the powder and not set it off. HUHHHH? First of all remember what the primer looks like. There is a little anvil pressed into the top of the cap. Got that? That little anvil causes the primer flame to split into three or in some primers four individual flames. No matter how the cartridge is placed in the chamber at least one of the flames is going to be pointing down. Now about that flame. The primer is a explosive compound that responds to impact. (compression) A primer made out of nothing but an explosive compound would be useless. Why? because the explosive mixture is so small that the flame from the explosion would not be hot enough to get all the way into the case and start the powder on fire, especially the stick powders and slow burning fire retardant coated powders. So the primer mixture has fibers in it. These fibers are set on fire by the exploding mixture and are launched into the case full of powder by the explosion. It is these burning fibers that actually set the powder on fire. (Remember an explosion is a detonation and that is when all the molecues turn into a gasses state simultaneously) So with the small amount of explosive compound available in standard primers there must be something extra to make sure the powder is caught on fire. That is the fibers and they are shot into the case. And what do they do even if there is only a very little smokeless powder laying on the bottom of the case? Well they obey the law. You know the law of Gravity. As they are still burning when they are exploded into the case they fall to the bottom of the case, which just happens to be where the powder is. But not all of them fall, some are launched faster than others and they blow the length of the case and then hit the base of the bullet and bounce around the inside of the case. These bouncing burning particles also hit the powder at the bottom of the case. So you can see that primers cannot flash over the powder. And especially cannot fail to ignite the powder no matter where it is laying. Yes I know that there has been tests run that shows the position of the powder will make a difference in the velocity and accuracy of the shot. That has been proven. But no one has proved that primers can flash over powder and not set it off.
Primer myth #2
Handling primers with your bare fingers will cause them to fail. NOT.
First of all do you not think that the manufactures of primers want their reloading components to fail? Of course not. And do you think that the Army wants any bum ammo in their soldiers magazines? Better believe they do not. So what has that have to do with sweating fingers? Simple all primers have a protective water and oil proof coating injected into the top of the primer cup. That is what you see when you look down into the primer and see that red or green or black color. When it is dry it seals the primer and does not allow even oil to get into the primer mixture. Your little finger oil is not going to even get to first base with the primer mixture. By the way, finger oil does not run. If you are thinking of oil as oil or maybe like WD-40 type oil that is called penetrating oil, the oil in your fingers is not anywhere near this type of oil. If it was and could spread itself around or penetrate there would never be any company selling hand cream. Now about spreading itself around. There are cases (many of them) on record by the police dept's all over the world of evidence that was stored for years being checked for finger prints and they were found and the culpert was convicted. If the finger oil was like penetrating oil the finger prints would no longer be there withing a few hours or days. The oil would creep away and you would have no finger prints but just a bloob of finger oil. So you see your finger print oil does not crawl into your primers and kill them. Even if the protective oil proof coating was not there. The reason is that those little anvils again. You cannot actually touch the primer mixture. It is under the anvils. You could put a finger print on the anvil but that is it. I have tried to kill primers by soaking them in penetrating oil and found that weeks later the dang things still went BANG when I applied heat with my soldering iron. ( I was making tie clasps out of empty cases with a good primer in it, but finally had to settle for a fired primer.
Sarge the myth buster