hybrid cartridge protoype without burst disk

[POLAND_SPUD]

You need some new material

Damn I am getting old

Better to add one time complexity to the fill rig than complicate every cartridge, this is how I see it:

Me approves


soo when are we going to see some flying brass ?

[al-xg]

I feel I'm missing something on that last quick exhaust fill rig sketch.

Is there another valve involved not represented?

[jackssmirkingrevenge]

Weren't you meant to be venting the filling chamber on disconnecting the schrader ?

Shock pump, independent schrader opening and disconnection.

You should use some sort of quick release plug, or even just an o-ringed threaded cap.

Yep, there are simpler ways of going about it, most of which involve turning all or part of the rig into a projectile

soo when are we going to see some flying brass ?

Not tonight, there's a kilo of prime ribeye and 8 pack of finest epoxyland beer in the fridge that suggests I will be putting cartridges on hold for today

I feel I'm missing something on that last quick exhaust fill rig sketch.

Is there another valve involved not represented?

You're perfectly right, I was still thinking air spring pop-off when I drew that, and to work it would require a separate schrader. The piston would be air tight, you fill the space behind it to just enough pressure to resist the mix pressure you intend to achieve, fill the main chamber from a separate valve and it automatically pops when ready.

An actual exhaust valve as described earlied might look something like this:

[Labtecpower]

Not tonight, there's a kilo of prime ribeye and 8 pack of finest epoxyland beer in the fridge that suggests I will be putting cartridges on hold for today

Makes fine targets when empty
You'd better speed up, i'm also designing a full auto now

[jackssmirkingrevenge]

Makes fine targets when empty

Can't use local ones, it would give away my location

You'd better speed up, i'm also designing a full auto now

Damn! *machines*

[HunterT]

Makes fine targets when empty

Can't use local ones, it would give away my location

Yeah, but we don't know what Epoxyland beer looks like.

[Labtecpower]

Can't use local ones, it would give away my location

Doesn't matter to me, I already know it
You can give them a layer of masking tape.

Damn! *machines*

The design I posted will cost me about 10 euro's to make 5 pieces, not too expensive I think

At school I asked for the largest hand taps, and they go up to M24, so I won't have to use a very small bore

Yeah, but we don't know what Epoxyland beer looks like.

Google translator can read the text on it

[myinisjap]

Read through all 37 pages of posts and wondered why I didn't see anyone suggest casting/pressing in the projectile. I was thinking something similar to an actual bullet. I will put up a drawing of what I am talking about tomorrow.
questions only testing would answer
At what psi will the projectile try to separate from the casing?
Would the friction of the projectile being cast in place provide a good seal?

[Crna Legija]

.
questions only testing would answer
At what psi will the projectile try to separate from the casing?

That and the time it would take to cast ammo into it. Also a cast bullet probably wont do much damage, if it was lead the heat would melt most seals, epoxy would takes to long to cure and would stick to everything and is expensive.

Would the friction of the projectile being cast in place provide a good seal?

it wont be air tight.

[jackssmirkingrevenge]

Read through all 37 pages of posts and wondered why I didn't see anyone suggest casting/pressing in the projectile.

If you look atthis post it's pretty much what I did, but the projectile was swaged as opposed to being cast, putting a 4.5mm BB in a 4mm hole.

it wont be air tight.

When swaged it held pressure surprisingly well:



My only objection to this was the fact that as you're deforming the projectile, at best it would be inaccurate, at worst it could actually jam in the barrel.

It might work using pellets as opposed to BBs, but they would have to be loaded from behind.

Also, at 5x the combustion was enough to dislodge the projectile, suggesting that at higher mixes this relatively low "pop off" pressure would not allow the full power potential to be achieved.

[myinisjap]

i was thinking this casting this type of ammo


I am going to try and stop by the hardware store tomorrow to pick up some fittings, to test whether or not the design will hold pressure. And if it does how much it will hold.

[jackssmirkingrevenge]

I've tried that type of pellet, hopelessly inaccurate from a serious air rifle and a bit of a gimmick. Here's a review that agrees with me.

Casting as opposed to swaging is likely to result in a much lower pop-off pressure, especially as the tendency is for the casting to shrink slightly as it cools.

[POLAND_SPUD]

If you look at this post it's pretty much what I did, but the projectile was swaged as opposed to being cast, putting a 4.5mm BB in a 4mm hole.

I guess you could have designed a better 'detent' (or whatever you want to call it) for it

Was the tubing crimped ? I have no idea what kept the BB in place

I imagine that using a pipe cutter would be a good method to uniformly reduce the ID of the tube

[jackssmirkingrevenge]

I guess you could have designed a better 'detent' (or whatever you want to call it) for it

If you're using lead only, then jamming it in place is really the only way to hold it, there's going to be some deformation on the way.

Was the tubing crimped ? I have no idea what kept the BB in place

No, it was simply a 4.5mm projectile jammed forcefully into a 4mm tube.

I imagine that using a pipe cutter would be a good method to uniformly reduce the ID of the tube

Either way you're going to squeeze the projectile.

I suppose a diabolo shaped pellet would act the same way as a squeeze bore shell and retain its aerodynamic characteristics if diameter reduces evenly.

[Labtecpower]

I started working on a prototype today, otherwise I will just keep dreaming and designing, and that won't get me a working gun

Turned the backplug out of some red PVC, on some a very nice "mini" lathe.
(Emco maximat super 11) it works very nice, and the finish is very smooth, opposed to the lathe I normally work on.



Inventor drawing for the plug;



Also bought a pipe for extra building stimulation



23mm ID 27 mm OD aluminium pipe. I think it's plenty strong, as it is being used for construction purposes. (scaffolds is the right word? )