The Saw

[jitup]

I know the name is cheesy, it is just a development name so i can refer to it.

ok the good stuff

I am working on a inline vortex, the barrel is 1/4 in brake line that is 3 ft long. the "receiver" is made of 2 inch pvc. the barrel goes into about 1 foot into the receiver, giving the gun a balanced look the barrel shroud is 1 inch pvc (any smaller looks weird with the 2 inch chamber). nothing is glued so give suggestions.

question time

should I make the vortex block have a 3/4 or 5/8 bore? I found several examples of both.

what do you suggest I use for a spring to push the bb's? I want an 8 inch resivior so I don't run out in 2 seconds. I have a 2 inch washer that I will attach it to, to drive the baas.

P.sa. do vortex or cloud guns have better performance?

I know yo will all be very helpful, and thank you ahead of time.

should I make a step by step How To as I build this gun?

[FishBoy]

I'm not sure about the other questions but as for votex vs. cloud, vortex is definitely better; If I'm not mistaken the vortex block was created as a better feeding system for clouds. Basically, vortex- higher ROF, more consistent feed, more reliable, more air efficient

[jitup]

thats what I thought, thanks

[starman]

I know the name is cheesy, it is just a development name so i can refer to it.

I don't think it's cheesy but it has been used several times before.

You will invest more time and sweat into a vortex and if done right, you'll have a more consistant performer than your average cloud.

I suggest you build your block, maybe 2 or 3 of them at different sizes and find out for yourself which works best for your setup. There will be things you haven't thought of that will come up and you'll have to work through.

I wouldn't worry about a step by step at this point. Concentrate of getting your gun designed, tested and built. There's really no way right now to know a step by step process until you really build one. Take some notes as you go along and piece something together later when it's complete.

[MrCrowley]

should I make a step by step How To as I build this gun?

If not, you may still want to take pictures though. Just make sure you do everything right.

With my VAL piston cannon, I had to take pictures step-by-step for a school assignment, they became very useful when making the how-to.

[jitup]

Thats what I meant, after the gun was finished, But do you think people would be interested in a step by step,

I am makink the block out of hardwood that will be sanded smooth after completion, so making several blocks is no problem, I will post which size works best for me.

Still I am having troble finding a spring. I bought one that was a couple inches too small thinking I could use brute force to stretch it, I was wrong.

I will make the gun able to accept CO2 and air from a compressor or a transport tank.

Also, I want to know if I am supposed to take the adapter out of the top part of the blow gun, and screw my fitting into that, or do I leave the adapter in and screw the fitting into the adapter?

[jitup]

I, Know I am not supposed to double post but I was wondering if some one has an answer to my above posts, also i am having trouble making the block, it keeps spliting when I get almost 5/8 of the way through,
any help is appreciated.

[Davidvaini]

may I ask why you are going with a 3 foot barrel?

Going with a 3 foot barrel is not a good idea... also if you can get a different barrel other than breakline, it would make it better..


A lot of veterans on this site love brakelines as barrels but their ID is way off of an airsoft bb.

3 feet is really long for a barrel.. Personally if you use it at 125psi I would never go over a 24" barrel "2 feet". This is because of friction and the volume of air inside the length of the barrel itself.

As far as a spring is concerned.. A shotgun tube spring works really well.. You want a spring strong enough to push the BBS into the vortex block without being so strong that you cant compress the spring enough.

[jackssmirkingrevenge]

3 feet is really long for a barrel.. Personally if you use it at 125psi I would never go over a 24" barrel "2 feet". This is because of friction and the volume of air inside the length of the barrel itself.

Why not? With a constant airflow, longer barrel can only equal higher velocity, and as most BBMG theory goes, lower rate of fire.

[jitup]

thanks about the spring, never thought of using a shotgun spring. I think I may even have several spares for one of my pumps.
Can some one please clarify about the barrel, am still unclear due to conflicting arguments. Was thinking about putting an adjustable hop up, is this really necessary for this type of gun?

[jackssmirkingrevenge]

Technically, a longer barrel will give you a higher velocity, as the projectile is being accelerated for longer. As to whether shorter barrels give greater rate of fire, it's a matter of debate, but in theory this should be the case.

As to hop up, no one really talks about accuracy or range when using a BBMG - effectively what you have is a hosepipe of BBs so it's easy to adjust your aim, I wouldn't bother.

[Davidvaini]

I would bother with a hopup... Though range is never talked about with BBMGS it doesnt mean you shouldnt strive to get better distance. Especially if you are going to use it in an airsoft skirmish.

I have put hopups in BBMGS and I can tell a huge difference in distance.. Accuracy wont really get effected becuase you are sending out a birdshot effect on the BBs.

Theory points to a longer barrel reducing ROF but I have not seen it in real life application. Also If you are gonna use it as burst fire (best in skirmishes) then a longer barrel for the first .3 seconds of firing will have reduced velocity(more volume of air in the barrel to be initially pushed out.)

[jimmy101]

David, do you have any hard numbers to back up the benefits of a hopup in a BBMG?

In my chrony studies the velocities of the BBs (from a vortex) are all over the place. The hopup might help a bit with the lateral dispersion but it can't help with the varying muzzle velocities causing significant vertical dispersion.

Lets see, 0.2" ID tube (1/4" brakeline) for 0.177 copper/steel at 3' long, total barrel volume is 1.13in3 (0.019 L). Air is about 1.3g/L so the air in the barrel weighs about 25mg. (Unless I screwed up the math.) The BB weighs 330mg. Therefore, the 25mg of air in the barrel is pretty insignificant compared to the mass of the BB and any friction as the BB bounces along the barrel walls.

[jitup]

I am using metal BB's, so this gun is not going to be for airsoft. If this gun works out well, I might build one similar with a bigger bore and shorter barrel for airsoft. What method of hop up would be ideal for this gun. If I chose to add one, it should be easy to install and some what effective. thank you for all your help so far. I will post pics of the progress once the gun starts taking shape.

EDIT: I did not see Jimmy101's post when I sent this. Thank you for the hard numbers and for taking the time to share your results. I still encourage those who suggest a hop up to argue their point, I am trying to gather as much info as I can before I actually start gluing.

[Davidvaini]

I know jimmy that a hopup increases distance because of the spin caused on the airsoft BB. If you have expierence with airsoft guns like I do.. you notice a HUGE difference in distance..

As far as the volume in the barrel, your math is right but the weight of the BB is actually 200mg, not 330mg. Still the volume though little does have a small impact on the initial bbs.. I have noticed this in real life application but It could of been a different factor.

The hopup though does add distance because of the spin added to the bb.


But since this isnt for airsoft than distance isnt really important.

When I adjust the hopup on my JLS FN F2000 all the way off, the distance is around 80 feet. When I adjust the hopup to create more spin I get around 175 feet for a straight trajectory. When I adjust it even more the BB will curve up.. then drop down at level at around 200+ feet.

I'd say distance is increased.