I has semi/full auto!

Building or modifying BB, Airsoft, and Pellet type of guns. Show off your custom designs, find tips and other discussion. Target practice only!
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Gun Freak
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Sun Jun 26, 2011 8:33 pm

Lockednloaded wrote:The power should increase as you start running out of BBs and your chamber space increases. For most people this is a problem, how do you think your final version will have better consistency?
I too have thought about this... I dont think the consistency will be a problem but I think this effect is evident in all valveless guns.
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kablooie
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Sun Jun 26, 2011 11:13 pm

I am going to try to make one. Just a fitting that is plugged then I will make a small hole in the plug. How big should the hole be?
Hmm, I have no idea how small the hole should be. If you're set on making your own, I'd say start really small, try it, and then enlarge it based on trial and error. I wouldn't rule out just buying a needle valve though, they aren't too expensive (~$10 if I remember correctly), and are adjustable.
If 1/2" doesn't work for your .177, it probably won't work for me either :P
Yeah, that's probably true. I can't help but think though that there's a certain diameter that won't cause so much jamming. Another idea, and something that I'd do in an instant if I hadn't already made my stock/shell for my gun, would be to use a chamber around 1/2" and bend the outlet from the chamber so the chamber is tilted down in relation to the barrel, causing the bb's to naturally roll backwards (towards the non-barrel end of the chamber). I've found with my gun, that shooting at un upward angle is an effective way to avoid jamming.
Just a coiled chamber instead of a big one. It would eliminate jams because the chamber is only wide enough for one bb. Coiling it allows it to be longer in a smaller space.
Ah, okay. It seems like that would substantially limit the airflow and produce annoyingly weak shots when the magazine was full, as LockednLoaded pointed out.
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jackssmirkingrevenge
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Mon Jun 27, 2011 12:46 am

Gun Freak wrote:Just a coiled chamber instead of a big one. It would eliminate jams because the chamber is only wide enough for one bb. Coiling it allows it to be longer in a smaller space.
... rather a coiled chamber is the chamber - sort of like this - and it's wider than one BB (but not wide enough for two, it should be roughly 1.5 times BB diameter) in order to allow sufficient airflow.
kablooie wrote:It seems like that would substantially limit the airflow and produce annoyingly weak shots when the magazine was full, as LockednLoaded pointed out.
There are many factors to consider:

- in a normal unregulated BBMG, power goes down as pressure goes down. Should you add a detent and give a greater "chamber volume" as ammunition is used up, if anything it should flatten this curve.

- in typical operation, the flow of air to the barrel is not cut off when the chamber empties, but when the next BB blocks the breech. One of the biggest issues I've had with this type of design is that flow is cut off before the BB leaves the barrel, stopping it and causing the next BB to collide in the barrel, often bulging out the barrel. I believe the solution is to include some sort of interrupter as in these previously published designs:

Image

Image

One I get a bit handier with the Sherline I definitely want to give this design a go.
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PoloBack18
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Mon Jun 27, 2011 5:57 am

HI Ya everyone :)
Now im a total noob to the whole with the whole homemade airsoft/bb gun stuff so forgive any stupid questions :(

But iv been looking through the forums for a basic semi auto gun that i can use in a skirmish with some mates.
Now im from Australia so buying one is out of the question and i have a pretty limited experience with making things but i really wana give it a crack.

So i was just wondering if you could show me a blueprint or even make a vid showing how you made such a wikid gun :D
Or if anyone else has a link to a step by step semi auto airsoft gun that's pretty beginner friendly

Thanks :D
3VIL G3NIUS
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Mon Jun 27, 2011 6:16 am

PoloBack18 wrote:HI Ya everyone :)
Now im a total noob to the whole with the whole homemade airsoft/bb gun stuff so forgive any stupid questions :(

But iv been looking through the forums for a basic semi auto gun that i can use in a skirmish with some mates.
Now im from Australia so buying one is out of the question and i have a pretty limited experience with making things but i really wana give it a crack.

So i was just wondering if you could show me a blueprint or even make a vid showing how you made such a wikid gun :D
Or if anyone else has a link to a step by step semi auto airsoft gun that's pretty beginner friendly

Thanks :D
You should probably make your own thread about your topic rather than jacking somebody elses.
But I recommend a vortex or cloud BBMG as your first gun because those 2 designs are more simple than an effective semi auto design.
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Crna Legija
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Mon Jun 27, 2011 6:23 am

edit: posted in his thread
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wyz2285
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Mon Jun 27, 2011 6:36 am

Jack I had made your second design that you posted last year, there is a problem, before the spin pushes the bb, the air scapes first and pushes the bb too, so when you fire it, normally 2 bbs are loaded. BTW use a o-ring detent, it´s really good, increase the power and less air lose, with that chamber you have, probably 100 shoots if you had a o-ring detente.
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Mon Jun 27, 2011 6:53 am

wyz2285 wrote:Jack I had made your second design that you posted last year, there is a problem, before the spin pushes the bb, the air scapes first and pushes the bb too, so when you fire it, normally 2 bbs are loaded
The dimensions need to be tweaked in order to avoid this happening, this is definitely one of my projects for 2011 now that I have the means to do it :)
hectmarr wrote:You have to make many weapons, because this field is long and short life
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wyz2285
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Mon Jun 27, 2011 7:01 am

Oh so good luck then, I´m going to wait to see if you can put is to work :D then make a copy.
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Gun Freak
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Mon Jun 27, 2011 9:52 am

BTW use a o-ring detent, it´s really good, increase the power and less air lose, with that chamber you have, probably 100 shoots if you had a o-ring detente.
I was not able to get the right sized oring. Every time I tried, it was too big or too small and they all ended up blowing out th barrel because it wouldn't seat right :P
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Tue Jun 28, 2011 8:13 am

Gun Freak wrote:I was not able to get the right sized oring. Every time I tried, it was too big or too small and they all ended up blowing out th barrel because it wouldn't seat right :P
Use a tight one, drill it a little bit until it fits then epoxy it to the right place. It worked for me.
Last edited by wyz2285 on Wed Jun 29, 2011 8:18 am, edited 1 time in total.
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Gun Freak
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Tue Jun 28, 2011 9:42 am

I tried drilling one before but I didn't epoxy it. Consequently, it blew out the barrel :tongue3:
I like rubber washers because you can easily adjust the pop pressure.
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