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Semi Auto Shell loader

A place to ask general spud cannon related questions.
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Unread postAuthor: kablooie » Mon Aug 13, 2007 4:52 pm

I do live in the states and I googled Big Lots, there is one sort of near me, are they necessarily cheaper than, say Home Depot? Thanks for the advice, I will see If I can get my dad to pony up for some of those things (I need most of my money for na air compressor/materials. I have always wanted to get a belt sander, so maybe I will.
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Unread postAuthor: judgment_arms » Mon Aug 13, 2007 8:55 pm

Is it cheaper the Home Depot? In a word: YES, Big lots is about half the price. I.E. Sawsall blade $.51 at Big Lots 1.99 at Lowes, can’t find them at Home Cheapo.

At tip to get your dad to pay, tell him it’s educational, and teaches responsibility, plus he could use ‘em any time.
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Unread postAuthor: jackssmirkingrevenge » Mon Aug 13, 2007 9:49 pm

I think the best approach with such systems is to keep it simple - have you taken a look at my cartridge fed pneumatic prototype? It uses the air flowing through the cartridges to blow back the bolt instead of a separate piston.
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Unread postAuthor: judgment_arms » Mon Aug 13, 2007 10:06 pm

Yeah, the Wookie gun works on the same principle; or, more accurately, doesn’t.

Edit:
Just realized how rude that sounded, sorry jack, no offence, it’s just simple ain’t always effective.
But when I design my guns I rely on Mikhail Kalashnikov’s words “all that is complex is not useful, all that is useful is simple.” The trick is learning were simplicity must be sacrificed for effectiveness and vise versa.
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Unread postAuthor: jackssmirkingrevenge » Mon Aug 13, 2007 11:32 pm

None taken - after all, my prototype worked ;)

Some things are necessarily complex - you can't build a car without moving parts - so there is a limit to which you can simplify, but in general, it's the simplest solution that works best, perhaps not in performance terms but certainly in reliability, so it's worth the extra creative effort.
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Unread postAuthor: kablooie » Tue Aug 14, 2007 12:37 am

That prototype is really neat, Jack, I am not sure If I will make it, though I have never made custom epoxy things before, and though I know there are tutorials for that, I think I might make a revolver design. It would not necessarily be true semi-auto, but I assume I will have a little bit of time while waiting for my chamber to fill that I can use to manually advance it. Maybe I will make it truly semi-auto somehow. I like the idea of having the loading mechanism out where I can get at it instead of shut in a magazine that will almost certainly jam at least a few times. What should I use to seal the cartridges? a coupling with a rubber ring (gasket?) on the inner lip of the coupling, or a cam lever coupling like on Revolver X?

judgment_arms- Thanks for the advice, I will try it. If all else fails I could just get on his nerves and annoy him until he pays me to leave him alone.
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Unread postAuthor: jackssmirkingrevenge » Tue Aug 14, 2007 1:15 am

I use epoxy because that's the material I have to hand - I think the real talent in spudgunning is taking an idea and fleshing it out using the resources that are available to you.

I think a revolver would be more complicated to make, due chiefly to the difficulty of aligning the chamber with the barrel. You can draw some inspiration from the Webley-Fosberry automatic revolver that used the recoil to cycle the cylinder. By making a similar pattern on the cylinder, you could have a ram that actuates with each shot (as per your original design) which via the grooves in the cylinder turns linear motion into rotational motion.
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Unread postAuthor: kablooie » Tue Aug 14, 2007 2:08 am

That is true, but if I used the resources immediately available to me you would be seeing a whole lot of pen guns. :lol:

Oh, yes. I hadn't thought about that. I would probably use a piece of wood to attach the chamber to the barrel. It would have to go on top of the gun to avoid the revolver part. That would be a pain, though it would just get in the way. I like the idea of the ram rotating the cylinder, that could be the start of making it truly semi auto. The only other dilemma would be sealing each cartridge. Maybe I could have something that would seal it during the shot but blow forward as well. (a repair coupling?) Thanks for all the help!
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Unread postAuthor: jackssmirkingrevenge » Tue Aug 14, 2007 2:12 am

kablooie wrote:The only other dilemma would be sealing each cartridge. Maybe I could have something that would seal it during the shot but blow forward as well. (a repair coupling?) Thanks for all the help!


That could be a solution, in the same way the Nagant pushes the cartridge forward to seal against the barrel.
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Unread postAuthor: kablooie » Tue Aug 14, 2007 2:03 pm

Does the Nagant move the shell or the breech? here is an idea I had. The Couplings would either blow-back by themselves (possible?) or Icould make some type of lever to do it manually.
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Unread postAuthor: hi » Tue Aug 14, 2007 2:10 pm

@kablooie-

im pretty sure that the nagant's cylinder moves foward when the trigger is squeezed. you see that thing between the barrel and cylinder that looks like a spring? i think that is what creates a seal between the cartrage and the barrel. then it moves back after it has fired so that it can revolve and line up the next round and move foward again.

so to answer your question, both the breech and the shell move.

notice- i think thats how it works, but i cant garentee it. if i made a revolver thats how i would do it. im pretty sure im right, but the world will never know unless you google it. :lol:


edit- i didnt see your diagram. its a good idea, but it would require alot of work. i think that the Revolver X works something like that.

second edit- i wonder when spudgunner's will reach the technological limits of pvc pipe.
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"physics, gravity, and law enforcement are the only things that prevent me from operating at my full potential" - not sure, but i like the quote

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Unread postAuthor: judgment_arms » Tue Aug 14, 2007 2:20 pm

Kablooie, if you want repeater capabilities I suggest you make a bolt gun, simple but effective, versatile, reliable, oh and did I mention simple?

Revolvers are complex pieces of machinery, and unless you know a gunsmith or have a revolver you can take apart, you’d best wait a little on this.
Trust me, I tried to make a revolving carbine, it’s not easy. Didn’t get past the cylinder, and mine was going to be manually advanced, you rotated the cylinder by hand, no linkages, only a lock to keep the cylinder from free spinning.

You’d be better off with an automatic than a revolver, in my opinion at least.
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Unread postAuthor: kablooie » Tue Aug 14, 2007 2:23 pm

Oh, I think I understand now, the force of the shot pushes the cylinder back into it's position. So maybe I could have the repair couplings stationary and the cylinder move. now that I think about it that wouldn't entirely solve the problem, because it has to seal on both ends. I might end up using a ram to force the couplings back.

judgment_arms- sorry, I didn't see you post. I see what you mean (I think so anyway), I should probably take smaller steps. Jumping from muzzle loading to semi-auto/revolver is a but much I guess. Is there any particular bolt action (I assume a bolt gun is not semi auto. Am I wrong?) that would be easier to make semi auto in the future?
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Unread postAuthor: judgment_arms » Wed Aug 15, 2007 10:15 am

Kablooie, if we keep on spoon feeding you like this we might as well make the gun for you :)
Okay, one last bit:
The green is the bolt, red is ammo, and the blue fuzz ball is were the chamber/valve assembly would be attached.
The bolt handle (not shown) should ride in an “L” shaped groove. When you want it to cycle automatically you block off the locking area of the “L” groove and put a LIGHT spring on the bolt/charge handle, some people use rubber bands.
I’m trying to avoid giving you step by step plains as this is quite simple (at least in concept, the actual construction is by no means easy), and if you can’t figure this out perhaps it’s best that you stick with muzzle loaders, for your sake, and those around you.

Anywho, do some research on machine guns and sub machine guns, particularly the STEN gun.
But first research bolt action rifles and more importantly the Crossman 1377/22, 2240, 2250, 2260, and their predecessors and the Benjamin Sheridan air rifles. The diagram bellow is roughly based on the bolts of the afore mentioned air guns.

Best of luck to ya’
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Unread postAuthor: jackssmirkingrevenge » Wed Aug 15, 2007 11:44 pm

I had been thinking about an adaptation of my cartridge fed pneumatic, with the cartridge funtion replaced by the bolt to maximise air efficiency, as per attachement.

I'm not however experimenting with a 6mm version of the following (from this page) in the hope of achieving full auto with a constant flow of air.

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