Electromagnetic firing pin?

B

bushidomosquito

New member
So what about using an electromagnetic coil to throw a firing pin? I've been toying with building a .40 S&W carbine (think mech tech conversion sans glock) and got a little stumped on the firing mech. I know all of the tried and true designs are used for a reason but I was testing a 24v relay and was amazed at how fast and hard it would snap even against a fairly stout spring. Aside from the obvious problem of having to rely on a battery for operation it seems like trigger pull and lock time could be reduced to a minimum. If another coil were used to hold a lightweight bolt closed against a permanet ring magnet the problems of gas operation and heavy blowback bolts slappin' around would be eliminated as well. I'm a machinist, not a gunsmith, but I have a very good understanding of firearms design and will turn an idea around and around in my head until all the bugs are out. I think this is just the place to find some guys to tell me all the reasons it will or won't work. Any thoughts?
 
tank round pins

Sir:
I wouldn't have one on a sporting rifle but some tank rounds have a set-up where the firing pin is imbedded in the primer and then it is electrically fired.
Harry B.
 
I take it you are talking about an electrical actuator to drive a firing pin against a percussion primer, not an electrical primer as in Harry's artillery piece or Remington's Etronx. Can you fit a solenoid to drive a firing pin in the space of a mainspring? If not, why bother, except as a design challenge?

One writer many years ago said that he expected to see advances in locking systems based on then-new high strength permanent magnets. Well, it hasn't happened yet, but maybe you are the guy. What with the inverse square law, it looks to me like a magnetic breechblock closure would function as delayed blowback. As soon as the magnets started separating, the attraction would drop off fast and the rest of the cycle would have to be sprung. Unless you are talking about way more magnet than I am.
 
Permanent magnets attract steel filings and loose rust and will clog things up. You want to avoid them. Electronic triggers have been around for awhile, and use a small electromagnetic solenoid to release the sear, but they do not try to use them to strike the firing pin directly. You end up needing dramatically bigger batteries and a dramatically bigger solenoid actuator to do that. It is not an efficient use of energy if you can tap into cartridge energy to cock the gun. Moreover, common solenoid valves and actuators have enough coil inductance that without a high voltage supply, they will not admit current fast enough to actuate any faster than current firearm lock times. Maybe in the range of 5 or 10 ms or so.

Anyway, electronic triggers can be made to feel very sweet (click a paddle-activated Microswitch sometime), and small solenoids can pull sears on a cocked firing pin and spring. Any attempt to get a solenoid to strike hard enough to fire a primer directly is going to add batteries and steel the size and weight of a battery powered drill, at the very least.
 
Thanks Unclenick, I wasn't quite sure about the power requirements/battery size and the issue with permanet magnets on the bolt face pulling in shavings seems pretty obvious now.
So how heavy does a bolt need to be for proper .40 S&W blowback operation?
I'm thinking 16" barrel and maybe a 22lb. recoil spring.
 
You could probably copy the bolt weight/springing of a Marlin Camp Carbine, add 5%, and remove weight if necessary.

I tell ya, the rare-earth magnets are incredibly strong. I'm not sure they are appropriate for inside the action of a gun, but they really hold. My friends and I fly high-end R/C sailplanes, and people are now using the magnets to hold the wings on to the wingrod/joiner, and the holding power two aspirin-sized magnets generate is wild. The down side is they can shatter if you let them snap together in an uncontrolled manner, so that should probably be designed out. I can tell you from personal experience they will pinch the heck out of you.

re the trigger: Do you even need a selenoid? What happens if you use a Li-Poly battery to recharge a little condenser, and electrically fire the primer? You can squeeze so much energy into a 3S lipoly these days it's unreal.

Think how simple the trigger group will be with no sear, disconnector, hammer spring, hammer.

Paintball guns have gone to electrically actuated triggers for some years now. The idea there is the trigger can "ramp" where you get one shot for one pull, five for three, and full auto after that, etc, with a 15 ball-per-second limit. Not good for what youre talking about, but you might look into the design.
 
You can't fire conventional primers electrically, unless you want to try to make a heater cook one off, which would be far from instantaneous and still would require big batteries. Conventional metallic cartridges present a virtually continuous metal surface which makes an essentially perfect Faraday shield. That is why you don't hear of static electricity setting them off accidentally. It would require a special electronic primer.
 
You are also going to have to make sure that any permanent magnet never receives any kind of impact/shock loading.
Even the new ones will demagnetize if struck enough times.
 
electro-pin

Sirs:
On the throne I read about a varmit rifle with a fairy colored laminated stock, a water tanlk(?), guages, lines - a real abortion!
Surely they wear, "lace on their pants!"

I feel identical about electronic triggers - Remington tried it and it evaporated quickly! We need rifles made out of steel, not plastic (I know about e-poxy bedding) - you know what that is? It's a way to cover up poor bedding!
Oh! Am I getting old!
Harry B.
 
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Just to clarify, I'm talking about using a solenoid to throw a firing pin into a conventional primer. Nothing fancy, just replacing the entire trigger, sear, hammer, disconnector group with a microswitch and solenoid and li-poly battery in the stock. A few R/C car batts. will provide all the juice I'd need. I figure if a spring can do it then a coil magnet can to. Also thinking about a couple of (shock isolated) half-ring magnets around the chamber and breech face to help hold the bolt closed and remove the need for lots of bolt mass to do that job. The magnet strength can be fine tuned by moving them farther apart until the action cycles properly.

Aside from the barrel, there wouldn't be any place for steel in this particular project (sorry Harry). Everything would have to be as nonmagnetic as possible and that spells titanium. There are tiny ring magnets that could get my ti firing pin moving toward an energized solenoid with a quickness. The receiver would be a piece of 1.5" titanium tube and I can machine the bolt from a fairly hard beta grade ti an well.

While I fancy myself a good machinist, I'm still no gunsmith and certianly no expert on the subject of magnetics so if I'm being specific enough, can anyone tell me what I'm missing?
 
Just to clarify, I'm talking about using a solenoid to throw a firing pin into a conventional primer. Nothing fancy, just replacing the entire trigger, sear, hammer, disconnector group with a microswitch and solenoid and li-poly battery in the stock
Click to expand...

Would work fine and can be done............In my opinion the unit would be undependable........Over time.
I would not want my life to depend on an electrical circuit....
Mechanical components can be inspected and replaced as needed....Granted we have alot better components available to us now in the electronic field, I have seen microswitches / solenoids last 15 years in extreme conditions without a hiccup and I also have seen them fail after several cycles...........But once a mechanical sear is inspected and tested to work, I have never seen one fail, between inspections....But I am only 41 years old, so maybe I haven't lived long enough...
 
solenoid have been used in paintball guns for years now with no one lookin back.

i always thought electo-ingnited primers would be a nice idea for cartridges it would dramatically reduce the size of a firearm by removing things like the sear, hammer, mainspring, fireing pin ,etc. and replaceing them with an electrode for a fire pin,and an ingniter conected to the trigger.
 
All a paintball gun has to do is release some gas from a tank.
It takes a pretty decent blow to set of a primer.
You are going to need a relatively large solenoid and batteries to back it up.
Solenoids take current, and a strong one needs a lot of it.
 
Hey teeroux, it's been done. Look up Remington Etronx.
The Fusil Electrique shotgun, made in France, imported here by Abercrombie & Fitch (the original one) in the 1960s is too old to show on the Net, but it had all-electric ignition.
 
Anybody ever read W. W. Greener's book? The Gun and its Development. He mentions an electronically fired gun in the late 1800s.
 
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