Hammer valve (Soon-to-be)semi-auto gun

[The_Guerilla_Guy]

Hi there fellow spudders,
after following the site quite a long time (not only this site, but quality it has ) I decided to build a semi-automatic gun that would just consist of parts you can buy everywhere. Thats because i have no access to any higher machines, im happy I own a screwdriver

Im going to build a stock asap, I´m thinking of some hot glue covering painted black so the somewhat gettoish design is hidden

Enough talking, some pics(notice that the gun isn´t fully assembled, as I´m missing a single part to connect the barrel and that barrel and magazines are also missing. Some diagrams will be added though)

[jackssmirkingrevenge]

Looks like it would work well, how does your valve look internally?

[The_Guerilla_Guy]

Looks like it would work well, how does your valve look internally?

I edited a pic to the top. basically its a screw with a washer and metal plate srewed to the end. I drilled a hole into the end of that endcap until it fitted nicely. might be leaking a bit, but I haven´t found a proof for that ;P

I already tested it without a barrel, everything is airtight and at about 7 Bar it gives a nice bang Without a hammer i didn´t manage to get more than two shots out of it, because i hit it to hard

[jackssmirkingrevenge]

Looks good but there's quite a lot of "dead space" (volume between the valve and barrel) which makes it less efficient, what calibre will you be using it for? If it's airsoft or 4.5mm BB, it would be better to use 1/4" or 1/8" parts for the hammer portion, you'll get more power from each shot.

[The_Guerilla_Guy]

Yes, there is some dead space, but im going to use it with an 1/2 inch barrel and some steel balls that fit it. Also, that is all i have when it comes to parts, since I have to walk (dont have a drivers license yet) about ten kilometers to the next hardware store, which has become somewhat difficult concerning the temperatures here but maybe I´ll do that in the near future. my first problem is the magazine. I thought about a spring loaded tube in a tee connected to the barrel. But wouldn´t it be a waste of power to just load the bbs into the barrel without a bolt closing the gap into the magazine?

[jackssmirkingrevenge]

I thought about a spring loaded tube in a tee connected to the barrel. But wouldn´t it be a waste of power to just load the bbs into the barrel without a bolt closing the gap into the magazine?

As you can see, the next BB effecively blocks the magazine so very little air is wasted provided the tube in which the BBs has an internal diameter very close to the BB diameter.

[The_Guerilla_Guy]

Hmm ok, I´ll try that then for the moment. i hope to find some nice HPA tank with a remote regulator as youz showed me the other day. That would be a beast. any idea if it is possible to recock the hammer to power a full auto? I thought i could build a tee where the elbow is now, leading it just infront of the hammer, but that would be a huge lot more dead space.

[jackssmirkingrevenge]

any idea if it is possible to recock the hammer to power a full auto?

I tried and failed, but it's not impossible

[The_Guerilla_Guy]

Think this may work?

[Crna Legija]

it looks like it might, you'd probable need 200+psi

[Gaderelguitarist]

Im going to build a stock asap, I´m thinking of some hot glue covering painted black so the somewhat gettoish design is hidden

So you intend to essentially cast a stock out of hot glue? That's a new one.

since I have to walk (dont have a drivers license yet) about ten kilometers to the next hardware store, which has become somewhat difficult concerning the temperatures here

Someone is dedicated to building stuff.

While your idea for a self cocking hammer looks doable, the proportions need to be tweaked a little. Don't walk twenty kilometers to find out that you need more parts, or didn't design it well enough. The little sear at the bottom looks like you'll have the ability to do semi and a slow cycling full auto if it all works as planned.

[FighterAce]

since I have to walk (dont have a drivers license yet) about ten kilometers to the next hardware store

You dont require a drivers license for a bicycle

[jackssmirkingrevenge]

While your idea for a self cocking hammer looks doable, the proportions need to be tweaked a little.

It certainly needs "tweakability", you're going to have to vary bolt and hammer spring strength/travel and perhaps hammer weight until you get it working satisfactorily.

Here's a design I had come up with incorporating a sleeve type loading mechanism, never built it though:

[The_Guerilla_Guy]

So you intend to essentially cast a stock out of hot glue? That's a new one.

I dont think so. I think I saw a grip made with something similar, a blowgun casted in some sort of glue, but I don´t remember who it was. But I agree as I haven´t seen a whole stock made out of it.

You dont require a drivers license for a bicycle Very Happy

Yes true, but I normally go there from school, to which I get by bus XD and riding a bicycle when the whole street is frozen is just funny when you can watch other people do it

It certainly needs "tweakability", you're going to have to vary bolt and hammer spring strength/travel and perhaps hammer weight until you get it working satisfactorily.

I could make the lower spring tweakable by addind a screw to the end to loose the strength. The upper spring should do fine as its only there to get the bolt pack in position, which doesn´t have to be extremely fast at least for semi-auto. Hammer and bolt weight would have to be tried several times though I think.

Here's a design I had come up with incorporating a sleeve type loading mechanism, never built it though:

This is nearly similar to a design i came up with yesterday, basically the air pushes the bolt back, creating something like a virtual second chamber. My only concern is that, to get the full power, this tube would have to be the same length and diameter as the actual barrel, wouldn´t it?



Edit: Ok, i see I´m too dumb to attach an image. Pic added to attachment.

[jackssmirkingrevenge]

This is nearly similar to a design i came up with yesterday, basically the air pushes the bolt back, creating something like a virtual second chamber.

That's actually quite a good idea

My only concern is that, to get the full power, this tube would have to be the same length and diameter as the actual barrel, wouldn't it?

Not necessarily, depends what pressure you're using. If you're using 8 bar for example, the tube can be 7 times smaller than the volume of the barrel and it will work.