Posted on 06/11/2005 6:06:45 PM PDT by rudy45
Before anyone jumps all over me, I DID do a search. Here is what answers.com says:
A primer is a small, disposable copper or brass cup, 4 to 6mm in diameter (standard sizes are 0.175 inches and 0.210 inches for handgun and rifle cartrdiges). In the cup is a precise amount of stable, but shock-sensitive explosive mixture, with ingredients such as lead azide or potassium perchlorate.
Here is my question: if we were to take apart an UNFIRED round, and look at the primer, what would we see? I get the idea that the primer is a ?sealed cylinder (like an oil drum)?. Then, inside this sealed drum is the lead azide or potassium perchlorate ?powder?.
So, when the firing pin strikes the primer, the material inside, being pressure sensitive, explodes (even though the the primer is a sealed container)?
I am assuming that the primer is necessary because the force of the firing pin is INsufficient to detonate the powder directly? Why, then, was I able (as a boy) to make rolls of caps go "bang" by hammering them or loading into a toy cap handgun (assuming the caps were filled with gunpowder rather than primer material)?
The relationship of primer to powder seems analogous to that of tinder to kindling or fuel, when making a fire.
Thanks.
Sorry, "revoler" = "revolver"
The bottom of the cup shows on the exterior of the cartridge. If you look at a bare primer, you see a "Y" shaped spider that is the "anvil" the firing pin crushes the priming compound against. The compound is put in wet and dries into a thin wafer. It is generally covered by a very fine metal foil, and then the spider at the open end.
SO9
Aha... now I understand.. I always wondered, until now, why the priming compound didn't get mixed up with the gunpowder, assuming (correctly) that the primer is a cup rather than a sealed cylinder. Because the priming compound has dried, and is solid not loose, there's no problem.
If you are really curious, head to your local gunshop and ask the proprietor your question. Chances are he or she will open a package of primers and show you how they are constructed.
L
LOL I should have been clearer. Let me try again...
IF we HYPOTHETICALLY were to take apart an unfired round (realizing that doing so is EXTREMELY dangerous and should never be attempted), what would we see when looking at the primer?
Is this better?
Thanks.
As I said before, you can satisfy your curiosity for about a dollar. That's what a hundred primers cost at my local Gander Mountain.
Also there's no difference between a revolver primer and a semi-auto primer. Primers are sorted by size, of which there are four:
Small Pistol
Large Pistol
Small Rifle
Large Rifle
When the primer is struck by the firing pin, the compound inside explodes shooting a flame through a hole in the bottom of the brass case which in turn ignites the smokeless powder inside the cartridge.
I hope that helps.
L
The reason is very simple... the powder in a roll of caps used in a capgun, is essentially, the same material as found in a cartridge cap... an explosive that can be detonated mechanically.
In fact, the roll caps were a development out of an early firearm ignition system from the muzzle loading days. Most post flint-lock muzzle loading guns required a copper cap filled with fulminate of mercury (an impact sensitive explosive) be fitted on a steel nipple with a hole into the firing chamber. The hammer of the gun would strike the cap, ignite the fulminate of mercury, which, inturn entering the firing chamber through the hole in the nipple, would ignite the black powder in the chamber.
The placement of the "cap" was cumbersome and difficult, especially with tired, cold, wet, or dirty hands. Some shooters used "cappers", a spring loaded magazine deviced made of brass filled with caps, to make the job easier. However, some innovative firearms manufacturers developed a mechanized cap feed system for their guns that used a paper tape with a small amount of the explosive placed between two strips of paper glued together. This paper tape was advanced with each shot over a strike plate with a hole leading to the firing chamber. Cocking the gun after loading the powder, wad, and ball, would advance the paper tape into position with a fresh load of primer powder.
This paper cap system added a degree of complexity to the guns that was prone to breakage. In addition, the paper tape with its powder was not waterproof or even humidity proof. Users found they had more misfires with this method of ignition.
It was soon outdated with the invention of breech loading guns using cartridges that included primer powder as part of the cartridge. In rimfire rounds, the sensitive primer was placed all around the rim of the cartridge, in "pinfire" the primer was struck by a pin that stuck through the cartridge base wall (the French like this method), and in "centerfire" the cartridge's primer was the cup shaped cap placed in the center of the cartrige's base.
The paper tape ignition system survives to this day as a toy.
Don't forget Berdan primers.
The example shown resembles a shotgun primer.
Rudy, I have to say it's very frustrating in answering your questions. I wish we had a Freeper who lived near you to help you in your shooting quest.
One of the posters mentioned that you could go to a gunshop and ask. They are usually very helpful. Just stay out of the WalMarts and try for a small family owned shop.
Please don't misunderstand. I always like reading your threads and I'll do everything I can to help. I did notice there are better experts than me who usually answer much more precise than I do.
Keep the threads coming. We'll help you get that expert rating.
And a primer is really nothing more than a generally smaller version of that cap inserted into a small hole in base of the cartridge.
Exactly.
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