Do fixed firing pins add strength to the lockup vs transfer bar?

T

TruthTellers

New member
I was using some empty cases with the dead primers still in them as a snap cap to dry fire a new revolver I have that has the firing pin on the hammer when the thought occurred to me to test the lockup after the hammer falls and see if there's less movement than if there was nothing in the chamber. Sure enough, I did feel a little less play when I had an empty case in the chamber and this was after already hitting those primers a few times deepening the crater.

Now it's got me wondering what affect does the contact between the firing pin and the primer have during actual firing on the overall lockup of the revolver and is there an added strength of a fixed firing pin on the hammer vs that of the transfer bar method where the firing pin is under constant spring pressure?
 
Unless you have a rebounding hammer, I would offer that lockup of a
hammer/firing-pin-protrusion/primer/case/rim/cylinder "system"
is the same even if you stick a transfer bar in the middle of that mix.
 
I don't think lock-up after the round has fired means anything. What's important is lock-up and end shake before the round fires -- in other words, is the cylinder/chamber always in the exact same position when the hammer falls.
 
The term "fixed firing pin" refers to the firing pin used in some open bolt submachine gun designs, where the firing pin is a protrusion machined in the bolt face to serve as a firing pin.

It is "fixed" in the sense that it is not a separate part, and is always sticking out the distance that a regular firing pin travels forward, and so fires the round when the bolt closes.

In revolvers, the term is "mounted on" the hammer (if a separate piece) or just the hammer, or "hammer nose" or firing pin, when it is an integral part of the hammer.

and no, it does not affect the strength of the lockup, either way, hammer or frame mounted.
 
Howdy

As already discussed, the slight reduction of cylinder motion caused by a firing pin trapped in the dent of a fired primer will have no affect on lockup because the bullet will be long gone before the primer has been fully dented.

I do suggest you stop using fired primers as snap caps and instead invest in some actual snap caps.

The purpose of a snap cap is to gently cushion the impact of the firing pin as it comes to rest.

When the hammer slams into the frame as it comes to rest against the frame, the forces of deceleration are astronomical. I worked in the defense industry for many years, and we had instrumentation that could simulate the affects of deceleration, literally what happens when something comes to a sudden stop, for instance falling onto a concrete floor. Acceleration and deceleration are expressed as multiples of the force of gravity. Written as G. You have probably read that when a rocket is launched into orbit astronauts experience about 3Gs, or 3 times the force of gravity. Jet fighter pilots can experience 9 Gs before they pass out from lack of blood to the brain, that is why they typically wear G suits that put pressure on their legs to keep blood from pooling in their legs.

When a hammer slams into the frame of a firearm, the G forces approach infinity. Not 10 Gs, not 100 Gs, it approaches infinity.

With firearms with long thin firing pins, like the firing pin of a S&W revolver, when the hammer comes to a sudden stop against the frame, the tip of the firing pin wants to keep right on going. It does not happen often, but I have seen the tip of such a firing pin snap right off because of the G forces exerted on the narrow cross section of the firing pin.

When using spent primers as snap caps, after a few impacts the primer has been permanently deformed. It can no longer cushion the firing pin because it has taken on the shape of the firing pin at rest. The result is that without the cushioning affect, the tip of the firing pin will want to keep right on going when the hammer comes to a sudden stop.

Snap caps are specifically designed to cushion the firing pin as it comes to rest. Some use a spring, some use a resilient plastic. Snap caps can be home made by removing the primer from the primer pocket and filling it with a resilient substance. Hard rubber erasers, the type used for ink erasers can be used. Regular pencil eraser rubber is too soft. Some folks fill a primer pocket with silicone rubber, but I do not recommend that, silicone rubber is too soft will give way too much when a firing pin strikes it.

I recommend the snap caps made by A-Zoom. The purple ones. I use them in my firearms when I need to drop a hammer.

https://www.lymanproducts.com/brands/a-zoom
 
Driftwood, I'd love to buy some snap caps, but they're not made in .32 S&W short and IDK if the .32 ACP caps would have a thick enough rim and be close enough to the recoil shield to cushion the pin. So, looks like I'll have to make my own.

Would JB weld be an acceptable snap cap or is that too hard? Where could I get these hard rubber erasers?
 
Nanuk said:
JB weld is too hard. The whole point of the snap cap is that it rebounds while the FP hits it.

https://pricecloser.com/product/217...ap+Dummy+Caps+Size:+32+S&W+Short+(6+Pack)

Why is it imperative to use THAT revolver?

You could size some cases and fill the primer holes with silicone? That may work for a while.
Click to expand...
Who said it was imperative? If I'm gonna buy snap caps, I'd like to be able to use them for ALL my .32 revolvers I currently have or may buy in the future.
 
There is no such thing as 32 S&W Short.

There is 32 S&W, the earlier version, sometimes called 32 S&W Short, and 32 S&W Long. There is also 32 Colt New Police which is identical to 32 S&W Long except the bullet shape is slightly different. 32 S&W Long has the same dimensions as 32 S&W except the case is shorter.

poGF4OyWj





A-Zoom makes snap caps for 32 S&W Long. The purple ones are made of aluminum that has a hard anodize finish on it. If I was you I would buy a set of A-Zoom 32 S&W Long snap caps and cut off the front so they can be chambered in a 32 S&W chamber. The shortened snap caps could also still be used in a 32 S&W Long chamber.


I must be showing my age. Some ball point pens used to come with an eraser on the end, just like on a pencil. The eraser on the ball points was harder than the soft eraser on a pencil. You could also buy erasers that you held in your hand to erase mistakes. You could buy them half and half pencil eraser on one end, ink eraser on the other end. The eraser for pencil was pink, the ink part was a dirty white. I'm sure your local stationary store still sells these. You take a razor blade and cut up the ink eraser to fit into primer pockets of cartridges. Cut it a little bit oversized so when you jam it into the hole it will stay.

No, silicone is too soft. Easy to apply, but it is too soft. JB Weld is too hard. It has to be rubbery.
 
Last edited:
There is one brand of snap caps with brass "primers", spring loaded to yield under the firing pin.

Your Hollands Royal deLuxe probably came with snap caps having horn inserts.
 
Silicone, rubber, erasers, epoxy and such offer literally NO protection to firing pins. The firing pin simply pierces them.

Hard nylon or spring loaded brass snap caps are the only way to go.
 
You must log in or register to reply here.
Back
Top