8 Gauge breech loading signal cannon (dial up users Beware)

[GGaskill]

One could add a light weight counter spring that only bears when the pin is forward and would retract the pin but not effect the firing significantly.

[Double D]

We are getting there George.  The firing pin could have a ring in the middle with a retraction spring on the front and firing spring on the back.  But you are going have to time everything so when the pin is cocked it doesn't pull the pin out of the breech face pin hole and out of the retraction sping. 

So much simpler to make two parts a firing pin and striker.

You could also work the latching mechanism to cam the pin back when the breech block is opened.

[Powder keg]

I think the second cotter hole will work good for a safty? It will keep the pin from moving forward and hiting the primer. It will also keep it away from the breech end of the barrel when opening and closing the door. I'm trying to keep these as simple as posible.

Wes

[Michael Az]

I guess there is something I didn't understand. I should have said before "With the striker not protuding beyond the striker housing face." Seems like it would work, but I'm not familiar with this type action.
Michael

[Double D]

Wes, that will work until the first time it's forgot.

[Powder keg]

Just to let you guys know what I have so far.

The end of the firing pin measures .312" I was going to machine a "tit" on the end to engauge the primer. I was also going to bevel or radius the big part a bit to keep it from hanging up on the breech face. I messed around with it a bit (before machining the end) and it does hang up when you open or close the door. Crap!!!!!

I am looking and I think I can make the housing in two pieces. That way I can machine a stop for a weak spring on the bottom of the pin to gently push it back when not cocked? Back to the drawingboard

Also, There is no latch. The weight of the door is pleanty to hold it shut. It slides down over the pins and their heads keep everything tight.

Later...

[GGaskill]

You should be able to get the positioning right by adjusting the spring lengths.  As long as the mainspring doesn't hold the firing pin against the breech, the weak spring should be able to push the firing pin back against the mainspring and out of the way.

[Double D]

First my apologies to you guys with your highly sophisticated CAD programs, you may not be able to read this drawing made with the old PAD technology   



Make a two chambered striker body.  Put the spring loaded Striker in one side and the retracting firing pin in the other.  Make  caps or breech plugs to retain them.  In this example the firing pin is retained with a breech plug and the striker has a cap.   Doesn't matter which you use. THe hole for the firing pin should be a taper from the inside out.

The firing pin should be constructed so that its over all length is shorter than the oal from the inner surface of the striker chamber to the breech face.  This way when the striker is fully released and resting over the  firing pin hole it will push on the firing pin but won't make it protrude.

You should also put some sort of decorative knob on the striker stem to make it easier to cock. Just make the stem long enough so the knob does not hit the back of the striker body when released.

This is a basic inertia firing mechanism.

[EL Caz 66]

DoubleD,

Thanks for your use of old PAD technology to explain your logic on this firing mechanism. Now I understand cleary what your talking about... Thanks for your input! boy thats why I love this place I've learn so much from all of you..

Ed

[Michael Az]

I wouldn't put a taper in the firing pin hole.
Michael

[Powder keg]

Well, I rebuilt the Firing mechanism. The firing pin is one piece like before and there is a light spring on the bottom and a bigger one on top.



I assembled everything and took the test barrel outside. I inserted a shell that just had a primer and closed the door. When the pin was pulled there was a sharp pop It worked!!!! I fired it three more times and it fired every time

I think it needs to be a bit longer with a slightly longer spring? The dimple left by the firing pin wasn't very big? I don't know exactly how big it's supposed to be? Maby the dimple is smaller because of the shell not having any powder in it? What'y think?

Thanks for all the input, Wes

[GGaskill]

How does the depth compare with the protrusion?  How much headspace do you have?  I would expect the pressure of a loaded round would make the depth even less if it did anything.

[Powder keg]

The protrusion is .045 and the dent is probably .008. Not exactly sure what "head space" is? Is it the space between the primer and the pin? If so, I have about 3/16".  I'm looking at this and my light spring could be shortned slightly moving the pin closer to the primer. I'll try that tomarrow.


Wes

[Powder keg]

By the way DD all my stuff is drawn with PAD 4.0:O)

[GGaskill]

Headspace is the difference between the cartridge rim thickness and the maximum distance between the front of the rim recess and the breech block at its farthest back.  So, for the sake of argument, if the rim thickness is .050", the recess depth is .055" and the free play front to back of the breech block on its screws is .005", the "headspace" would be .055" + .005" - .050" = .010".  That effectively shortens the firing pin protrusion by .010" plus moving the breech block in reaction to the striking of the primer probably absorbs some of the firing pin energy.

What size primer does an 8 ga shell use?  I am guessing it is an all brass shell?

[Double D]

Wes,

You made the same thing except different, and it should work.  Pin protrusion should be  .050 to .055, .060 max.

I am not going to go into a long discussion on  head space, I am just going to tell you how to check...Shade tree method.  Deprime a case. Put a  .005 piece shim stock on the head. Chamber the case and close the door. The door should not close or be very tight and close with force. If loose you have excess head space and you should correct.

PAD 4.0, doesn't that use paper without lines?  To techie for me.  I had to upgrade to PAD 2.0 when i couldn't get graph paper any more.   
 

[Powder keg]

DD, I sketched it up today and started building it before I saw your sketch(which was nice by the way). I think Headspace is irrevilant in my case because the firing pin can protrude 1/8" past the end of the door. I think my problem is the return spring doing too good of a job. I'll correct that after work tomarrow and see what I have. I'll also post some pictures of the test barrel I made.

Wes

[Michael Az]

I sure don't know anything about 8 gauge ammo components, but it is entirely possible they use a heavier material than say a 12 gauge thus requiring a stronger striker spring. As you are working on something that can't be verified easily it will just be a matter of experimenting with the spring.  If it will go off consistently and not puncture the primer, you got it. I might note I would be sure to use a true radius on the firing pin to avoid punctures of the primer.
Michael

[Powder keg]

Hey! That gives me an Ider. I have a 12 gauge sleeve that I built for 12 gauge blankes. I'll try that tomarrow also. Better not do it in town though

[Double D]

Sounds like we should have the long discsussion on head space.  Firiing pin protusion and Headspace are not the same.

Excess head space can cause bulged primers and shell heads, misfires and even rupture of the cartridge case. In the simplified version it is the safe depth of your cartridge in your chamber. It is the most critical measurement of a cartridge gun.  It must be correct for the gun to safely function.

Firing pin protrusion is also critical.  To long  a firing pin will cause piercing, to short, misfires, To large will cause cratering, to small ruptering, piercing or misfires. The critical test in testing protrusion is firing a loaded round. Test with just a primer is fine, but the pressure from a  primer and the pressure for am a loaded round are very different.

Check your headspace, and adjust your protrusion.
   

[GGaskill]

Make sure your weak spring is not going solid (compressed so there is no space between the coils) and limiting firing pin travel.

[Powder keg]

I spent about 5 hours messing with it today. I have it working pretty good now. I was having trouble with the big springs, and getting the pin to rest in the right spot. I think I have it figured out now, though. The springs would not fully rebound the first 2 or three times I fully compressed them. If I trimed them to legnth and then fully compressed them 2 or three times they would be to short. So now I compress then several times and then I can trim them and they stay the right legnth The primers vave a better dent now.

I'll make that test carriage tomarrow and get some video. I wanted to do that today, but I spent all my time messing with springs:O) Now, what style carriage?

Wes

[GGaskill]

I would make one of those yoke mounts like the fancy salute guns use.  Is this going on a boat? See these.

[Powder keg]

I got quite a bit done this weekend. I have almost all the firing mechanisms done. I got the test carriage ready to go. But I didn't get wheels on it yet. Here are some more pictures.







As soon as my wife gets home from work tonight I'll go get some videos of her going off  

I was going to mark the barrel with metal stamps, but have been reluctant because it is very hard to get them to look nice. I ran across some info on the net and am going to try it. I ran asross it here http://www.homegunsmith.com/cgi-bin/ib3/ikonboard.cgi?s=216c160aeca17a2e8407bc5d98a69557 It is near the bottom under October 24: signing my name. He uses a product called "the Personalizer Plus" sold by Jantz Supply. http://www.knifemaking.com/ It uses Electricity to eatck the metal and the results look very profesional. Has anyone here used this?

Later, Wes

[Powder keg]

I might try this one instead. They have a pretty good website here http://www.etching-metal.com/index.htm Also they have a kit to make your own stenciles with a regular printer.

[EL Caz 66]

Yes, that will look nice.. Great Idea!!

[GGaskill]

There are two tricks to marking metal with stamps to get a good result.  First, use some black plastic electrical tape to define the bottom line of the lettering.  Place the bottom edge of each stamp against the tape while positioning the stamp.  Horizontal spacing is done by hand but that is easier and less obvious when not perfect than letters going up and down.  The other trick is to file or abrasive paper polish the area that was stamped to remove the raised metal around the stamp indentations.  This will give you only the depressed area as the marking and looks pretty good.

Try it on a practice piece first to see how it works and what it finishes as.

[Tropico]

YES ., It looks awesome.

[Rickk]

Those electric deals look nice.

I use metal letter/number stamps in my part time leather business quite a bit. To use stamps on round surfaces and get them to come out nice would be a major skill to aquire.

If you (or anyone else) tries to use regular stamps, one of my tricks was to make up a jig that holds the stamp in place. The holder is square tubing. You weld the tubing to an appropriate fixture that locates your stamp in the proper place. This guarantees that the stamp will be square and also all the characters are on the same line. It is still tricky to get the spacing to come out uniform.

When I made the jig, I discovered that when they make metal marking stamps they deform the handle part of the stamp a bit in the process of making the stamp. I had to grind all the high spots off the sides of the stamps to get them to all be straight and the same size and fit the inside of the sqare tubing nicely. The inside of the square tubing got opened up a bit with a file as well..

The other trick to master is knowing how hard to hit each character. For the same depth of penetration the letter "I" takes way less force to hit than the letter "W" for instance.

Everything I have done to date has been flat, not round, and I have messed up quite a few items getting the hang of it. I have thought of rigging up an arbor press to use stamps in but it hasn't happened yet.

Again, those electric things look cool. If you get one, let us all know how well it works.

[Powder keg]

Took some night video:O) Something was lost though? It plays a lot brighter on the camera? Also this is lots louder than it is on the video. I think I peed a bit the first time it went off Hehehe You can hear it echo. Enjoy.....




Later, Wes