Calculating firing pin energy

[PercyShelley]

One of the requirements for the US military pistol competition that resulted in the selection of the Beretta 92 as the M9 was that the pistol should have a certain amount of energy for reliable ignition of (sometimes hard) military primers.

How was this measured? Was it just the amount of energy the spring stored when the hammer/striker was cocked? Is that even a reasonable way to measure the energy the firing pin will have? Surely a substantial portion will be lost due to friction when the firing pin smacks into the back of the slide face.

 

[1SOW]

The same stored spring energy will give much different results with changes in: the hammer mass, the firing pin mass and/or the firing pin spring weight. Lengthening the FP will also increase the strike force.
The FP isn't pushed into the primer. It flies into the primer after being struck by the hammer like a baseball and bat.

Point your pistol straight up. Drop a new wooden pencil , eraser first into the bbl. Drop the hammer. How high it flies will change with any change in the variables I mentioned.

 

[Jim K]

I am not sure how lengthening the firing pin will increase the strike force except that it makes the firing pin a bit heavier. Firing pin energy can be calculated but usually is tested empirically, as by using a copper dummy cartridge and measuring the depth of the dent left by the firing pin.

Jim

 

[rcmodel]

And a typical 1911 will stick a pencil in a ceiling tile 8' off the floor.
Because the inertia firing pin has almost unlimited travel. Out of the breach-face.

But a typical Glock, or SIG, or S&W revolver with limited firing pin travel will barely move it at all..

Yet, each of them is going to set off a primer Every Time you pull the trigger.

Shooting pencils has nothing at all to do with reliable enough firing pin energy, or speed, to fire a primer.

It has more to do with hitting the primer fast enough to initiate the chemical reaction to make it fire.

Not how much energy it has.

You can slowly crush a primer completey flat in a vice with 5,000 pounds of force and it won't go off.
Or you can shoot it with a BB Gun and it very likely will.

rc

 

[murf]

try this link: riflemansjournal.blogspot.com/2009/08/primers-it-dont-go-bang.html

murf

 

[MachIVshooter]

You can slowly crush a primer completey flat in a vice with 5,000 pounds of force and it won't go off.

In my experience, crushing a primer will very frequently result in ignition. Happened many times during seating operations with a hand priming tool. The friction of the anvil grinding against the cup as the two parts become distorted with the priming compound in their midst can cause detonation. Not reliable, but predictably will happen with a large enough sample.

 

[brickeyee]

"Surely a substantial portion will be lost due to friction when the firing pin smacks into the back of the slide face."

Say what?

A polished pin in a reamed hole that is oversize?

 

[1SOW]

I am not sure how lengthening the firing pin will increase the strike force except that it makes the firing pin a bit heavier.

Without changing any other variables, extending the firing pin is used in lightly sprung pistols to gain reliable ignition with harder primers.
I may be incorrect when I used the word "force". Whatever proper term applies, it can and does improve firing pin effectiveness with harder primers.

Additionally, making the FP spring slightly lighter will increase the resultant force of impact.

 

[Deaf Smith]

I use the pencil-with-eraser method when I can't actually fire the gun

Deaf

 

[fastbolt]

Dunno how Beretta engineers and the military testing folks decided to test firing pin energy. Might even have been different methods used at different times.

I can tell you that for their PPQ, Walther uses a copper crusher which is inserted into an adapter cartridge, which is then carefully seated in the barrel's chamber. The striker is released in the normal manner, which results in an indentation on one end of the copper crusher.

A dial indicator is used to measure the depth of the indentation, with a measuring tip being moved across the copper crusher until it reaches the deepest point of the indentation.

The results are measured against a set value of minimum acceptable depth (according to the manufacturer's engineers in the case of that Walther model).

It's not like there's a shortage of engineering tools and gauges for such things.