SpudFiles

Howdy, hope those of you in southern Oz are enjoying the 38 degree day.
Damm it's hot.

Anyhow........

A germ of an idea was spawned from another discussion on the forum yesterday or day before about the issues of pressure loss via a tube mag / breech.

How about an integrated mag/breech setup ? The idea is to carve a block of HDPE or aluminium into say 100mm x 100mm x 40mm. Drill two holes at right angles to each other all the way through on the main axis, one the outer diameter of your barrel and one the diameter of your projectile. The projectile sized hole penetrates the bottom of the barrel, forming a T junction.

Assuming a snug barrel fit and probably a forward and rear detent, the round should sit snugly in the barrel ready to fire.

Put a dozen rounds up the pipe, cap it with a screw in spring pusher and you have a sealed system. To the external view it would have the appearance of a STANAG type magazine (once you dressed up the block a bit) but would function as a standard tube mag. I know you could get a long way to the same thing with just a T fitting then cladding but I suspect the drilled block idea would give a tighter and cleaner end result.

Thoughts ??

It should work great, have a look at something similar:



http://www.spudfiles.com/forums/mk-iv-q ... 17926.html

Damn this iPad is fiddly, thanks Obama yeesh!

well I see one problem - you have to drill really deep holes and that isn't always easy

ohh and what's the point of it ? you can achieve the same result with a T... if you have access to machining then go for something more impressive like an aluminium block that combines both the T and a valve

I made a push button version of same thing. Uses a push rod piston type thing screw, spring, washer, 4 nuts rounded off. Placed inside a small tube 1.5in long ish with a hole drilled for bb, it pushes through .n boring epoxyed to a washer that is then dipped in epoxy and ground smooth after set. Pops out soooo sweet The mag is just a tube with a long weakish spring and a washer with an o-ring epoxyed to it pushes nly room for one bb in piston area. The mag sits same direction as barrel and push with ur after opening the breech. Just working on a pilot waste operated piston valve for semi auto minus the oring maybe.. unless I can get it just right. This would mean it would have to be at a different angle. Oh and blah blah blah I claim no responsibility for this idea. Just how I did it. Will post pic in next 24hrs when I'm done. Its drying as we speak. The push button version anyway. Might have to sit down with a piston valve expert to nut the nuts out.

I currently operate a similar assembly in my gun.

I use a T-junction and a short tube as magazin. Spring loaded to allow gravity independent loading.

You should keep in mind that magazine should be fast to change.
In this case the mag also has to keep the full pressure of the system.
So some engineering is necessary to solve that. I chose to build a bayonette locking system, but it is not that good sealed, so I loose some power with it....

I would advise to use a T-bolt.
A bolt comes in from one end and runs through the T --closing off airflow back into the magazine.
The ammo passes another tee wich feeds in the air.

In this gun I made ,..the first T ( ammo) is replaced by a simple hole,seen as a notch in the barrel... wich I later attached a magazine to.
I didn't actually use a Tee, but it's basicaaly the same thing.

The second T, wich is the brass ring you see around the barrel, is where the pressure comes from.
The ammo is pushed into the second tee by the bolt just past the port.



Or you could use a hollow bolt in stead of the second Tee...but that would limit airflow.

The bb gun im building atm uses the same system as brians. A bolt (mines a pnuematic piston) closes off the mag tube and pushes the bb just past a second tee where air is fed in. I use a mag that is inline to the barrel though for space reasons. Works the same as a sprung tmag

I deliberately didn't mention the fact that I used a mag parallel to the barrel ..
I thought it would overcomplicate the principle.