Semi Auto Marble Gun

[clemsonguy1125]

Well this is the gun Ive been designing and working on for the couple weeks. Its a basic one inch barrel sealing piston valve with a T Mag Detent. It has a spring so I can fill it from a from the chamber. Right now its in its early stages, Im planning a BFB, and I was to shorten the chamber, and reduce the ghettoness. I have not decided what to paint it yet.
Piston-Spoolt with rubber poper glued on
Pilot-Hose spray gun
Fill-Quick Connect
Chamber-22 inches of 1.5 inch PVC
[youtube]
[/youtube]

[Gun Freak]

Lol that piston is sooo super ghetto, can't wait till you clean it up and build the bfb and all that stuff. Nice job, I know I already said it but just for everyone else to see

[clemsonguy1125]

yeah it really is, I want one that I could shoot so I could see some improvements besides asthetics, I really need a better loading mech, right now I have a double feed about every 10 shots, Im open to any suggestions.

[Gun Freak]

I have a suggestion.... build a BFB! haha, What are you planning for the new piston?

[clemsonguy1125]

No im keeping the piston lol

[Lockednloaded]

The chamber is extremely overkill as I've told you in the chat. Reduce the chamber size, up the pressure (at least as much as you're comfortable with) I'm pretty confident you can get the detent working effectively when you get some real marbles.

[clemsonguy1125]

Ok thanks I'm going to as soon as I get a coupler I'm think I'll cut it down to 12 inches from 22 and do you know what size pipe most marbles fit in

[Lockednloaded]

it can be different based on which type of marble you use, marbles can even be different sizes in the same pack. for semi-auto you need consistent ammo, so I recommend you get some steel bearings with an OD matching you barrel's ID. If you want to stay with marbles don't cheap out on the dollar store assorted brand, get some consistent quality ammunition

[clemsonguy1125]

Ok I may just order some, I'm a fan of jawbreakers because they decompose and I don't have to pick them up in fear of my dogs choking on them

[Major Collins]

its not true semi auto ... its hooked up to a compressor which fills it up after each shot...

[Crna Legija]

we count that as semi auto anyhow because each pull of the trigger lets off a round, there anrt many non constant filled semis on here, the only one i can think of is btbs old shatt

[Major Collins]

yeah btb old shatter hand is a nice one also the "slider cannon" is a good one along with Poland Spud's mk3

[Crna Legija]

The mkIII and slider both are hooked up to a pre filled tank that fills there chamber after each shot, so by what you said before that aren't true semi ether

[POLAND_SPUD]

The mkIII and slider both are hooked up to a pre filled tank that fills there chamber after each shot, so by what you said before that aren't true semi either

Well, it isn't surprising that most guns are filled from an external tank. I Could have chosen a different design, let say the one used by BTB, but it wouldn't work as good.

Semis use a lot of air, just calculate how much air you need for 1 shot and multiply that by the number of shots you want to get. Ohh and don't forget that you need more than that - otherwise the performance will drop dramatically after each shot.

So sure you can build a gun that uses just one chamber but if you want to get 10 or more powerful shots the chamber has to be very large. BTB's gun could fire about 15 shots IIRC but with each shot the power dropped significantly.

The laws of physic are the same for both designs.
I suspect that this problem will be less pronounced with semiauto hybrids since fuels have a lot higher energy density than compressed air (JSR commenting in 3... 2... 1...)

[bighead33]

Semis use a lot of air, just calculate how much air you need for 1 shot and multiply that by the number of shots you want to get. Ohh and don't forget that you need more than that - otherwise the performance will drop dramatically after each shot.

yup pneumatic have a long way to come before they can stand up against the the big guns of today.