SpudFiles

I am currently stuck in the progress of my project of a BB gun, i need some suggestions or if anyone knows how to make a spring bolt action Airsoft gun please comment, NEED HELP of were i can get materials how to make it more powerful etc. if anyone has ever created one can you please send me some plans or blue prints, that would be great, thank you [/b]

I would generally advise against springers, have a read though these threads:

http://www.spudfiles.com/forums/spring- ... 18133.html

http://www.spudfiles.com/forums/mechani ... 22108.html

If youve ever disassembled an old springer air rifle, you'll know just how intense the springs inside them are.

It takes a hell of a lot of spring to get a air rifle pellet moving. It takes some serious metal to contain all that spring - and as has been pointed out, even a slight mistake with such forces can be very nasty indeed.

That isn't to say that it cant be done. Just that it shouldn't be by most people, and not to be offensive or anything, but if your asking for help/plans/ advice on materials then you probably fall into the category of "most people" who should avoid home building spring piston air guns.

If you are going to attempt something along these lines metal construction is a must... for that you need a decently equipped workshop.

You could probably make an over sized nerf gun out of PVC, or maybe some simple construction methods could cobble together a low powered BB plinker... but all told results wont be great, and it will probably end up being more dangerous to the user than it would the target.

Edit:
Looking closer at your pic - it looks a bit like you just have a probe hitting the BB with the springs force - the only way to make that "more powerful" is to put a stronger spring behind it (ok making the "hammer" part heavier might help too but it would create just as many problems as the stronger spring). But the same warnings apply, the stronger you make your spring, the more likely it is to damage you when a hand gets to be in a spot it shouldn't, or for the spring to fly out the back of the gun when the forces become too much for the material you made the launcher out of.

Building an airsoft springer, assuming that you intend to use it for playing airsoft (i.e., you're not looking to hit 500m/s or something...) doesn't require particularly big or dangerous springs. In fact, the ones you'd be looking at for this application probably wouldn't even take a finger off if you screwed up.

Assuming that you live in the U.S., McMaster-Carr should be able to meet all of your spring needs.

As to determining the strength of spring needed: in a relatively low speed application like this, it's possible to make some VERY broad assumptions on modelling the firing process and still get an output that's accurate to within ten or twenty percent (and guaranteed to be an overestimate, which gives you a bit more information to work with). In the simplest case, you could assume that the pressure is always constant throughout the system and apply P*V^γ = constant to adjust it between time steps, based on the position of the spring and the projectile. While this isn't a physically valid model, it will be close enough to at least give you an idea of required spring strength. Preferably, you'd incorporate into the design means to adjust the length the spring is compressed to for a shot to get exactly the performance you're looking for through testing.

If you're feeling excessively lazy, you could just take the spring's stored energy to be the maximum possible projectile energy, look up "typical" springer efficiencies, and guess at the muzzle energy from there. Due to the looser barrel fit, efficiency will probably be lower in an airsoft springer than in a pellet gun.

Also, as regards the piston hitting the projectile directly: bad idea. You'll damage the projectile unnecessarily and vastly reduce performance. Much better to have a sealed piston being pushed through a tube toward the projectile and use the air pressure generated in between them for the launch.

Finally, don't ever ask for plans to build anything on this site. Doing so implies that you don't understand the device in question well enough to design it for yourself, which means you shouldn't be building it at all.

it was my first post, no need to be so harsh, but i get your point and now i have moved on to homemade AIR rifles and have almost secseeded in making one

hey i think nobody wants to be harsh
If you take a look closely in the forum, you'll find that most of the active members play with very large amounts of muzzle energy/ velocity. That's the reason why we tend to "test" the new-comers.
have a good time browsing the website

thankyou i was planning on making one but after reading this and the other forums up the top i might steer away from it