The semi-automatic paintball pistol

[)DEMON(]

Granted but that would not be a controlled system unless the blowgun is semi-automatic and I need it to be controlled, each shot has to be consistant for use in paintball.

I think I might design a sear for semi-automatic use, I am not sure what to call it but the type of sear that only allows one shot per trigger pull. The chamber would need to be filled from a fairly slow flowing source to allow reset of the bolt.

[Antonio]

Jack, I did try some designs around something similar to your blowforward design, I kept on ending up with a much too big or long design than I would like and it was getting too complex as a semi automatic design.

I don't see how it could be more complex and less compact than this:

You have a point here. It is really basic once u take of the trigger 3 way valve. I think u should start looking at making this 3 way valve and c if its better than the blowgun>flow speedwise. I think this all looks good on paper, but it is more difficult to make it if you dont have the tools etc. But still I like this design bc its more controlled> good job!

[jackssmirkingrevenge]

I found that with my 6mm semi using the blowgun I got very little variation in velocity, maybe in the order of 20 feet per second as a total spread. In fractice, this would not be enough to affect accuracy. The disadvantage would be that since you have to "snatch" the trigger, it could be enough to throw your aim off.

If you're using a three way valve, it could be possible to alternately fill and pilot a piston valve in the same way a nailgun works, just a thought

[)DEMON(]

I also thought of that but then it would also be too big. This design combines that valve and the bolt instead of having the two separate but that would make a really nice semi-auto high power rifle, the piston set up.

[POLAND_SPUD]

a 3/2 valve is a 3way valve that can be set in two positions ON and OFF. a 5/3 valve is a 5way valve that can be set in three diferent positions... it simply gives more information....

Deamon when someone posts his design it implies that the others would discuss them... actually I would be happy if you pointed out the disadvantages of my design because I could have missed something and you comment might help me. I've asked what are the advantages of this design because it seems that it is difficult to build so I've been courious what are the reasons you want to go to such great lenghts...

I think you can excess the pressure rating of the valve. it is only a matter of wheather o-rings would seal well or not.

[)DEMON(]

a 3/2 valve is a 3way valve that can be set in two positions ON and OFF. a 5/3 valve is a 5way valve that can be set in three diferent positions... it simply gives more information....

Thanks, that is very helpfull.

Now that you put it that way I see what you are saying. Your design seems as though it would work fine but I think there may be a small problem. As the QEV is actuated pressure will decrease rapidly in the chamber and the bolt may move backwards before all the gas has escaped. I may be wrong though. It is too big for me though.
Advantages of my design:
-Compact
-simple
-very few components
-hand held
-controlled semiautomatic action
-minimal gas wasted each cycle

Disadvantages
-Will be difficult to construct
-may have flow problems with the 3way during high ROF

I want this to be as small and light as it can be, I want to have one of these made for myself so I can use it playing paintball, obviously a lot is not shown in the concept that will be needed for paintball but I am getting to that.

It should be easy to get the o-rings to seal if the machining is very clean and accurate, the prototype will just use a lot of lubricant.

I did some research on a machanical sear, it should be easy to make, much easyer to use and maintain than the pneumatics. The sear should be somewhat like that of a Tippman paintball gun, seen here: http://www.zdspb.com/media/tech/animations/prolite.gif Except upside down, it might actually be easyer to use a sear set up from a Spyder, and I should be able to just buy the parts and fit it into the design instead of custom machining small parts of the sear.

Then flow to the chamber from the reservoir will have to be limited to allow the bolt to return. I only made some basic sketches today, nothing worth posting.

[Ragnarok]

I don't see how it could be more complex and less compact than this:

Surely you mean less complex and more compact rather than vice versa?
Because I can see a lot of ways of complicating it and making it bigger.

[jackssmirkingrevenge]

Because I can see a lot of ways of complicating it and making it bigger.

I meant that specifically using the blowgun in conjunction with the blow forward breech need not be more complex than the diagram attached.

[Ragnarok]

Ah, so:

I don't see why it needs to be more complex... etc. Right. That makes more sense.