Re: New Gauss Rifle
..., Fri Mar 24 2006, 12:14AM

Determining how many turns is a tricky thing to do...

There are 3 basic parameters in a coil gun: voltage, current, and pulse length
The voltage will be determined by your cap bank (however high you charge it is your voltage)
The current/pulse length are inversely related to each other (ie higher current = shorter pulse), and the pulse length is directly related to the capacitance of the cap bank. The inductance/resistance of the coil is directly related to the pulse length.
So to tune the coil gun you need to change either voltage, current, capacitance, or change the inductance/resistance of the coil.
So once you have decided on the voltage/capacitance you are going to use, you need to decided how much inductance/resistance in the coil you need. You want the resistance as low as possible, but using bigger wire makes the coils larger/less efficient; so you need to find a tradeoff between the two that is most efficient. Most people just use whatever they can find in the 20awg-10awg depending on the energy stored in the bank.
But more importantly you need to decide on how much inductance (turns) you need. You want to keep it as high as you can (to reduce the current so you can use a cheaper switch), but if it is too long the pulse length will be too long and you will get 'suckback' where the coil is on after the projectile leaves so it gets sucked back in.
It is hard to calculate all of this, so most people just use a simulator and twiddle with the values until you get the highest efficiency. Unfortunately I have yet to find a simulator that takes into account the maximum pulse length before you get too much suckback, so you just have to figure it out on your own. If you use this simulator it gives you the pulse length. If you plug them in to this one it will give you a velocity. And you know the length of the coil. Because you want to pulse to have ended by the time the projectile is through the coil, you can take the length of the coil (in feet)*the velocity (f/s) and get the time. As long as this number is less that the pulse length you should be ok.

As to the 555, it is used for a plethora of uses.
I am guessing what you are asking about is a pulse generator used in IGBT based guns. Instead of using an switch that is on all of the time (like a scr) and tuning the coil to fit their bank, they use an oversized cap bank (more capacitance than is in tune with the coil) and use the switch to turn off the pulse when the projectile leaves the coil. This gives more efficiency, and makes the design more complex.

They are also used pretty extensively in the power supply to charge the cap bank. Both in boost converters and to drive a (or several) switch, and then the resulting signal is fed into a transformer to get the necessary voltage.

I hope at least some of that made sense...

Good luck!

Re: New Gauss Rifle
Simon, Fri Mar 24 2006, 01:14AM

So you want to make a coilgun? A gauss gun is something different. At least what I know of as a gauss gun.

I wouldn't recommnend a four stage if you aren't quite sure about the number of turns. Remember, a good four stage CG is made up from four good single stage CGs so experiment with single stage first.

Re: New Gauss Rifle
Remus, Fri Mar 24 2006, 06:22PM

Thanks Guys, that should help me getting up to speed. Hopefully, I'll be able to get a design going soon. 1 stage sounds good. 2 questions tho. does anyone know where I can get a projectile made? the steel bullets...and second, Simon, what exactly is a gauss rifle, if its a different thing from a coil gun? I thought they were the same thing, just referred differently.
Thanks.

Re: New Gauss Rifle
The Zander, Sat Mar 25 2006, 06:45AM

I've been building coilguns for quite sometime now, and i've found that the easiest (perhapes not THE best, but definately the easiest) way to calculate parameters for a coilgun are as follows

1. Decide on a projectile, i'd recommend finding somthing in the ~10-20g range for low power coilguns, but really it's totally upto you, just remmber that heavier projectiles may be slighty more efficent but will not travel as fast (if your looking for the holy $HIT factor, you need a light/fast projectile

2. Once you know the mass/length of your projectile you can determine an approximate final velocity using the forumla MV1^2=(0.03)CV2^2 where M is the mass of the projectile, V1 is the muzzle velocity of the projectile, C is the total capacitance of the capacitor bank, and V2 is the total bank voltage. this formula is a combination of the formulas for kinetic energy of a mass, and the formula for the potential energy stored in a capacitor. it assumes a 3% efficiency. and obviously you are going to need to isolate V1 in the above equation to find the velocity (i just have no idea how to write sqrt() signs using the forum interface)

3. Now you know the approximate final velocity of your projectile (emphasis on approximate) you can calculate hwo long your pulse length should be to maximize energy transfer. in order for this to happen there should be a magnetic field present around the coil (aka: current is flowing through the coilg) for the entire time the projectile is within the coil, AND NO LONGER. if the pulse length extends beyond this the magnetic force will remove kinetic energy from the projectile as it tries to pull it backwards. use the formula V=D/T. your projectile and coil should be the same length (imperical evidence suggest this is very efficient) therefore you are really just trying to find how long it takes your projectile to travel the length of the coil. say your coil is 3cm long, and your muzzle velocity is 10m/s (you can do better than this, it's just a nice number to work with). therefore your target pulse length should be T=D/V, T=(0.03m)/(10m/s), T=3mS (milliseconds).

4. now you can check you the coilgun simulator on barrys coilgun site (great resource for beginners like yourself) and design a coil with that pulse time in mind.

Just my $0.02
-The Zander

ps. i appologize in advance for any spelling/grammer errors inthe above text, it's late, enough said.

Re: New Gauss Rifle
Barry, Mon Mar 27 2006, 01:28AM

Zander, awesome post, nice description -- it's exactly the approach that I would recommend to anyone starting a new coilgun. So I'm just adding a "me too!"

Cheers, Barry
Also, here is a link to the coilgun simulator that will help you determine part values for a desired timing

Re: New Gauss Rifle
Quantum Singularity, Mon Mar 27 2006, 05:17AM

I have not yet come across any reputable site indicating the a Gauss Riffle is something specificaly different than a coil gun. The common defenition with a quick google search indicates a Gauss Riffle is a magnetic linear accelerator. That can include a whole host of different types of magnetic guns. Also, according to Wikipidia http://en.wikipedia.org/wiki/Coilgun

A coilgun (also known as Gauss gun, Gauss cannon or Gauss rifle) is a type of cannon that uses a series of electromagnets to accelerate a magnetic shell to very high velocities. The appellation "Gauss gun" comes from Carl Friedrich Gauss, who formulated mathematical descriptions of the electromagnetic effect used by coilguns.

The best site I have found so far that clearly explains the different types of coil guns is Coilgun Systems, try this http://www.coilgun.eclipse.co.uk/coilgun_basics_3.html
(use the arrows to view all 3 pages).

I beleive the term coil gun here on 4hv usually refers to the reluctance type coilgun. I have not built one of these myself yet, I have built a few different variations of inductance/reconnection type coilguns though. Good luck!

Re: New Gauss Rifle
Remus, Tue Mar 28 2006, 09:04PM

Thats some great Info guys. Thanks a lot. I'll keep y'all posted on anything new I come across while building this. Where would I get the projectile made though? I wanted to make it hollow point, with a helical cut into the projectile...maybe fill it with some epoxy. Any ideas where to do this or with what equiptment, if I were to do this myself?

Re: New Gauss Rifle
FastMHz, Tue Mar 28 2006, 09:56PM

I think generally you'd want your slug to be solid metal, not hollow or filled with nonmagnetic material. I make mine by chopping the head off a bolt, sticking it into my drill and using my bench grinder to make a point.

Re: New Gauss Rifle
Self Defenestrate, Tue Mar 28 2006, 11:14PM

I'm a fan of the drill and dremel aproach. Find a steel/iron rod of correct diameter and cut it to the projectiles length. Chuck it up and grind it with a dremel attachment for the desired point. This setup makes polishing real quick too.

Re: New Gauss Rifle
Simon, Wed Mar 29 2006, 01:44AM

If we're quoting resources, don't forget our wiki.

Some people have non-solid projectiles to avoid eddy currents (not an area I've investigated myself).

I just find a bolt/nail/screw that fits well inside the coil, cut it to size with a hacksaw and shape it with an angle grinder. Anything along those lines will result in a decent enough projectile.

Re: New Gauss Rifle
rupidust, Wed Mar 29 2006, 02:08AM

You can try fabricating the projectiles for yourself and hollow pointing the tip. But hollow pointing with basic tools takes a long time. Gauging does reduce eddy currents but also removes mass. For every gram removed is 1/2 a joule lost given that the speed is the same. Hopefully speed does increase to compensate loss of mass and added speed to bring up efficency. In my opinion, if one does not fabricate a few slugs of different lengths and compare the energy result of those rifled to those non rifled, then why does one make a slug in the first place.

Text and Image quoted from ACG-
"I use steel rods from common hardware stores. Measuring, cutting and pointing the raw steel bits is a fast process, about 2 minutes a projectile. However, 2 minutes feels like 20 when being inundated by the loud noise, sparks, and heat generation associated with forming metal. Polishing a projectile to a crystal shine, now that consumes a lot of time. Below is the systematic process I use governed by the tools I have.

Measure and mark the rod sections to approximate projectile length. Cut the rod into raw sections with a saw and metal cut off blade. Grind one end of the raw bits into a point shape with the raw bit inside drill/driver and metal sanding blade inside saw. Press the raw bit onto sanding blade at desired point angle while bit and sanding blade rotate in counter directions. Remove any excess length of this bit by grinding down the non pointed side with a saw and sanding blade. Polish the projectile using a drill press and sand paper. Alter projectile point angle with the coarse 60 grit sand paper. Buff the coarse finnish with the 220 grit sand paper. Apply the final shinny coat with the very fine 600 grit sand paper."

Re: New Gauss Rifle
Quantum Singularity, Wed Mar 29 2006, 03:08AM

I had an idea and I was going to wait and see how it turned out before I announced it, as I am not sure how well it will work. But it will save time and hassle making your own projectiles and only require 1 small cut (easily done with dremel and cut-off wheel). My idea was to use commonly available field points from archery. They come in a few different shapes, sizes, and weights, but of most interest will probably be the largest 'bullet point' ones available. They are already precesion made, and I beleive out of high carbon steel. The only issue I see is that they are lighter and rather stuby and not as long as what most people here use. But maybe for designing a compact hand held pistol they may be ideal? The only mod you haev to do is to cut off the small shaft that exits from the rear of the point. The sizes I have in the picture are probably the largest ones available, 145 grain bullet points. That I believe is equivelent to 9.4 grams and will be a bit less after removing the stem part. They are 5/16" diameter. Archery shops normaly sell them for around 20 cents each if I remember correctly.



Edit: I beleive the larger one on the right is 145 grains, the others are 125 grains (8.1 grams).

Re: New Gauss Rifle
Remus, Thu Mar 30 2006, 06:10PM

To Quantum Singularity:
The points Ive seen are hollow on the inside in order to attach them to the arrow. I'll have to check out these solid arrow heads.

@rupidust:

That sounds like a great idea, I'll give it a try. I might have to go and buy a grinder tho, how much do those cost?

@Simon:
Thats exactly what I was trying to do, based on various coil guns made by other people, Ive seen that rifling the bullet adds to speed, and reduces Eddy Currents. I'll try both rifled and non-rifled, once I get my coil gun finished up.

whats the average weight of a projectile in grams? I suppose if I just chop a piece of steel thats like 2 or 3 inches long, then measure the weight, that would work, but of course Id like to get an idea.

Before I forget, does anyone have a schematic of a charging circuit for the capacitor bank. I dont want to go waste 8 bucks on a camera just to strip out its guts. Id rather build it myself anyways, so I can custom build it for size. maybe solder some smd's rather than full size resistors/transistors. Thanks.

Re: New Gauss Rifle
Quantum Singularity, Thu Mar 30 2006, 06:37PM


The only hollow heads I have ever seen are for glue on type old fasion wood arrows. Any sporting goods or specialty store I have ever seen usually stocks exactly what I have in the picture above, atleast in the U.S. (not sure about mars though)

Again I dont know how ideal they are, but it would be an easy way to get a bunch of identical bullet shape projectiles with minimal fabrication.

I plan on trying the 125grain bullet points but I am focusing more on an induction coilgun for now. The reluctance cg will probably be later on this year.

Rifling... not sure how well this would work. For one thing for rifling to actually spin a projectile it has to be under high pressure against the riffling. Any drag on a small coilgun would probably kill its performance. There are ways to spin it ahead of time and launch it already spinning. I would worry about building a working gun and then trying to improve upon it. Good luck and hope it works out!

EDIT> I might have missinterpreted what you meant about riffling. Riffling is usualy a helical groove cut in the barrel. I think you simply mean slotting the projectile, which should reduce eddy currents, increase speed & efficiency (slightly).

Re: New Gauss Rifle
Remus, Thu Mar 30 2006, 06:50PM


Yea, I dont know what to call it. a helical groove cut but in the bullet, not the barrel itself...two birds with one stone...reduce Eddy currents, and increse the speed.just slotting it might reduce eddy currents, but it wont necessarily increse the speed or efficiency. The more arodynamic the projectile is the better the efficiency, or at least that what I understand of it.

Re: New Gauss Rifle
rupidust, Thu Mar 30 2006, 07:01PM

I do not think you need a grinder, never used one myself. The main advantage of self fabrication is choice. If your coil and cap arrangement match an exiting projectile like an arrow tip, thats great. But for experimentation you need to alter diameter, length, material, and tip till its just right. Raw rods of varing diameters and lengths can be gotten from Lowes, Home Depot, Ace and local shops easily and just one rod will produce more slugs then you will need, all for couple of dollars, assuming the pre-existence of tools of course. Pointed tips penetrate easier, flat tips hit/push hard but do not penetrate at lower energies, and hollow points do both, penetrate and hit hard.

Re: New Gauss Rifle
Remus, Thu Mar 30 2006, 07:06PM

So how do you make the tip like that? Ive got a dremel, will that work?

is this the right charging circuit to be used? Flash camera charging? <br>


mod edit- oversized picture- and don't forget to credit the source, Sam's Repair FAQ

Re: New Gauss Rifle
Quantum Singularity, Thu Mar 30 2006, 08:05PM

Rupidust is quite correct saying the main advantage of making it yourself is that you can make it any shape or size. The possibilities are endless if you are skilled and have the right tools. I am definately going to try my field point idea just to see how it works though. There are so many variables in a cg that you need to start somewhere, mine will be the size/shape of the projectile being fixed, and I'll design from that point on. Reducing eddy currents with slotting will reduce losses and possibly make it faster and more efficient. The riffling or slotting itself probably wont make it faster or more efficient due to spin, as its unlikely to spin very much. With heavier projectiles it takes alot of force to get spinning, and I doubt air pressure will make it spin very much under a few hundred meters/sec. FWIW I just determined my rifle shoots bullets that spin 857 revolutions per second. Even if you had fins on you cg projectile I doubt it would spin more than a few revs per second.

And about hollow point projectiles... usually this is to increase the expansion rate of the soft lead / copper jacket bullets. That wont happen on a solid steel slug. It might look cool though. If you want maximum shock transfered to a target with solid steel than a flat nose would be best, and pretty easy to make (might not even have to do anything).

Re: New Gauss Rifle
Remus, Fri Mar 31 2006, 07:35PM

well based off of one of the other coil gun sites, and their experiments, Id have to stick wth hollow point. The normal projectiles went through a can, but the hollow point projectile, went through it, and tore a section out of the can along with it. Im thinking of developing coil guns for hunting...so anyways that my view of the hollow point.

I still cant find where to get some steel rods from, anyone know?

Re: New Gauss Rifle
Quantum Singularity, Sat Apr 01 2006, 02:52AM

Well it might help us if we know were you live. I dont think you'll have much luck finding steel rods on mars . Around here it is available in any hardware store, lowes, home depot, or can be substituted with bolts, drill bits, pins (not little needles - pins for hitch recieves and suff) or various junk in my garage probably has steel rod pieces in it - or at a scrapyard.

I am sure a hollow point with sharp edges will do some damage to soup cans and such. And looking at it from a ballistic standpoint, a coilgun bullet is quite a bit different than a normal bullet. A full metal jacket bullet would be most similar to a cg bullet, and it is pretty darn rare to see a hollow point FMJ being used. Riffles dont often use HP either, simply because there is no need - HP's were designed for handguns to get the bullet to mushroom at much less energy as compare a riffle round wich will mushroom even with a pointed tip. A steel cg bullet is not going to mushroom, and for hunting there would be two routes to take; penetration or maximum shock. A pointed bullet would get you max penetration, and a flat or wadcutter (term used mostly in pellet guns and shooting competitions) would get you maximum shock. For example, small game arrow tips are flat to knock out the animal or simply deliver a huge enough blow to kill them. I have shot a ground hog with 3 pointed arrows and didnt kill it, however I have taken many deer with pointed tips (and some sharp blades). The hollow point that rupidust posted will have properties of both because it is slightly dommed and has a sharp edge it will have slightly less shock and more penetration than a flat nose. But more shock and less penetration that a pointed tip. Heck to be honest it might be a pretty darn good design, just depends on the application.

Re: New Gauss Rifle
Remus, Mon Apr 03 2006, 08:56PM

You say I can find something like this at a scrapyard? Im in Texas btw. hmm.... I wonder If theres one here in town....Would a junkyard have the rods? hmm....Im not too concerned about the hollow points. I thought that would be just neat, but Im trying to get the projectile first. then I figure things out from there.

Also I asked about the charging circuit...and I think rupidust responded... does a charging circuit really cost 22 bucks? or could I possibly build one cheaper...

(im guessing that youre trying to make a profit too):-D

I wish I could roll back the clock back to when I was in high school...I took three years of this stuff, and I can barley remember anything....

Thanks for the help guys...



On another note, Ive got some calculated values so far. I have a
Peak current density of 555 MA/m^2. Is that enough to limit heating? Im reading on the Magnetic Club site, and they say the current density should be higher that 1000 MA/m^2.
Another thing, does a wire length(of the coil) of 44 feet sound accurate, or is that too long?
Im going to try a single stage first...so that what these numbers are for. Ive got a projectile velocity of 35.24 m/s. My Peak current is 600A, with a voltage of 220v. How can I calculate how efficient my coilgun circuit is?

My 4th set of calculated numbers gives me something I like, and may just go for it. 150V, 600A, a coil length of 1.5" and 4 layers of 36 turns of 18 gauge wire each. Projectile velocity at 28.5m/s. I think that sounds way better, and more possible on my first try, then the first set of numbers...but my question about Effieciency and heat limiting still stand are yet to be answered.

Re: New Gauss Rifle
Yohan, Thu Apr 06 2006, 03:18PM

I know Yohan gets mad when noobies ask about how to make a coil gun

I don't recall ever getting mad when someone asks a well thought out question that didn't already have the answer posted somewhere in another thread.

Like this one:

does a charging circuit really cost 22 bucks? or could I possibly build one cheaper...

If your target voltage is <170vdc you can build a charger for about $2.00 and plug it right into the wall. How? Just rectify the 110vac coming out of your home wall outlet.

And this one:

just slotting it might reduce eddy currents, but it wont necessarily increse the speed or efficiency

Could not be more false. Eddy currents bad. Efficiency good. Getting rid of eddy currents boosts speed by reducing drag and increases efficiency which =

For steel rods - Home Depot - Lowes - Any hardware store - I would go with cold-rolled steel. It's easy to work with and very cheap.

What have you chosen for a barrel material?
What are your questions for efficiency and heat limiting, specifically?

Re: New Gauss Rifle
Remus, Thu Apr 06 2006, 07:51PM

[quote]

I don't recall ever getting mad when someone asks a well thought out question that didn't already have the answer posted somewhere in another thread.

I found a previos thread...

... that has to be the most ignorant post I've seen out of you yet.

This forum is dedicated to those in search of knowledge and you create a "Coilgun for Dummies" post. Shame on you.

Sorry, I may have misunderstood.

What have you chosen for a barrel material?
What are your questions for efficiency and heat limiting, specifically?

I might go with aluminum, tho I may stick with steel. Still doing the research so I dunno which is better.
As for heating limits, according to the Magnetic club site, the inductance should be over 1000uH, All of the calculated inductances so far in simulators have been way below that. Is that good or bad?

Also, I got two ques. Anyone know where I can find the legal limit of a projectile velocity out of a gun? And, how fast or how slow a projectile needs to be in order not to have problems injuring someone ( or shooting it through a wall)? Thanks!


As for the charging circuit, I need a small mobile circuit, that can run on AA batteries. turning 18vdc into 150vdc.

Re: New Gauss Rifle
Yohan, Thu Apr 06 2006, 08:12PM

Sorry, I may have misunderstood.

You did misunderstand. Read it again. That post was directed at an existing member who was counseling a newbie.

I might go with aluminum, tho I may stick with steel. Still doing the research so I dunno which is better.
As for heating limits, according to the Magnetic club site, the inductance should be over 1000uH, All of the calculated inductances so far in simulators have been way below that. Is that good or bad?

Conductive barrels are not good. I don't care if you slot them or not. The eddies can still spin up in a slotted barrel and jack your efficiencies. Look into polycarbonate. There are several other suggestions in the archives as well.

1000uH is huge...take the MGC with a grain of salt. The coils we used for our fastest and most efficient model ranged from 5u to not more than 500u with the armature at TDC.

Also, I got two ques. Anyone know where I can find the legal limit of a projectile velocity out of a gun? And, how fast or how slow a projectile needs to be in order not to have problems injuring someone ( or shooting it through a wall)? Thanks!

I wouldn't worry about that. I'll be quite impressed if you get a velocity even 30% of a low caliber air rifle.

As for the charging circuit, I need a small mobile circuit, that can run on AA batteries. turning 18vdc into 150vdc.

Why mobile? Why 18v? Do you realize how simple it would be to modify an AC wall plug to get your 150vdc? Perhaps you should do that first to at least get the gun calibrated and working well. Then, after you've learned a bit more, venture into power supply design. Or just pay the $22 bucks...

After reading your posts, I can see that you haven't been through the archives yet.
So I'll tell you what I tell every other new forum member. READ!!!! It's all in here. We'll help you if you get stumped.

Re: New Gauss Rifle
Simon, Fri Apr 07 2006, 04:11AM

Okay, the original swipe at Yohan was definitely pushing it, now let's cool things a bit. The issue in the last thread was cleared up as far as I know.


In short, don't make personal remarks and don't tell others what to post. If you have a problem, tell a mod.

Simon

Re: New Gauss Rifle
aahz, Fri Apr 07 2006, 10:22AM


Here, I just posted this: 12v to 450v+ Boost Converter

Re: New Gauss Rifle
Yohan, Fri Apr 07 2006, 01:03PM

With regard to small and mobile:

With a battery powered charger, the life of your charger is limited to the amount of energy stored in your batteries. Depending on the size of your capacitor bank, you may tear through a pack of AA's in one session. This can get expensive.

To obtain the velocities that you had mentioned in previous posts, you're going to need a fairly large capacitor. i.e. >>470uf especially if you're operating at 150vdc. Reason? The energy in your capacitors is .5CV^2...typically we use a small capacitance, larger voltage to get the energy you need to obtain the velocities you want. In this case, your V is relatively small so your C will need to be larger. If your C is large, you're going to have a small, mobile white-hot charger (if not properly sinked as aahz mentioned in his boost converter post - awesome little circuit btw )

It's your decision, but until you get it tuned, it would be wise to use the quasi-free energy coming from the wall outlets of your college/home. (quasi-free as long as you don't pay the e-bill )


EDIT: OR....use rechargeable AA's!!! Seems a bit redundant though...

Re: New Gauss Rifle
Desmogod, Fri Apr 07 2006, 02:21PM

Or a generator on a hand crank :P

Re: New Gauss Rifle
Steve Conner, Fri Apr 07 2006, 03:26PM

Well, then you could just build a crossbow with a winch for loading. That would cut out all the pesky electronics and it would be 50 times more efficient too. Try not to go too far off topic folks.

Re: New Gauss Rifle
Remus, Mon Apr 10 2006, 08:41PM

@ Simon: my bad. It wont happen again....I was a newbie.
@aahz, thanks for the boost converter, I'll give that a try.
@Yohan, Iwould prefer dealing with batteries, so that I dont blow my fingers up, or trip the breaker or somehting stupid, besides I live at home with my folks, and they wouldnt like it very much if I had random item plugged in the wall. I think Id rather stick with batteries. I was thinking about rechargeable batts tho...

Re: New Gauss Rifle
evilgecko, Mon Apr 17 2006, 09:00AM

Yeah for some reason I like to use low voltage as well. Or though I do wonder when I end up stepping down 240V with a transformer then using a boost converter to charge a 330V cap bank up from the 12V output. Its not the clean green way but hey I somehow feel safer doing that.

Re: New Gauss Rifle
Remus, Mon Apr 17 2006, 06:30PM

Ok, so Ive been searching around the net for legal muzzle velocities. I cant find where I can get any so I can know if my coilgun design is legal. Is there anyone that can help....Im in Texas....thanks.

Re: New Gauss Rifle
Quantum Singularity, Sun Apr 23 2006, 01:54AM

I have never heard of any 'legal' muzzle velocities before. What are you trying to be legal for? For it not to be classafied a fiream? Well, some air rifles can out shoot some firearms and I dont think they are classified as anything more than any other bb gun, so I doubt muzzle velocity is the deciding factor? I guess it depends what you plan on doing with it. If your trying to make something you can bring into a school for a project then even a squirt gun can get you arrested. If you are going to shoot it off in the back yard outside town limits that you could be shooting an elephent gun and it wouldnt matter... I dont think this is the right place to ask about the nitty gritty on weapon laws as most here are not going to be knowledgable in those details, especially since it changes from place to place. I am not even sure were you could go for such information. I have tried asking local police officers questions like this and have either gotton diffifing answers or uncertainty from them. All something has to be is 'suspicious' to warrant a law officer questioning you.

Re: New Gauss Rifle
Remus, Mon Apr 24 2006, 07:18PM

Well, When I build it...I would be using it in my backyard in the town limits...I thought someone her would know since y'all do this stuff all the time. And yes, there are legal muzzle velocities. If the City of Chicago considers 700feet per second an assult weapon, then other states have their laws also. I dont think I d walk up to an officer and ask"how fast does a gun shoot to make it illegal?"lol. that would be silly. Tho, I havent tried the library of congress...

Re: New Gauss Rifle
Yohan, Tue Apr 25 2006, 12:36PM

I wouldn't let muzzle velocity legality stop you from beginning your project.
The only way you could jump over 300fps (paintball gun velocities) would be to build a multiple stage induction coilgun and you're going to need a whole lot more energy than what you've got available to you now.

Start building/learning and you'll see. If you hit 300fps with 330v caps and only this forum and an Elec/Emag class as your guide, I'll put my head between my legs and kiss my own arse.

Re: New Gauss Rifle
rupidust, Tue Apr 25 2006, 09:39PM

Does your offer extend to .22 to 1 gram range BBs? Because if it does, Remus could hit that speed under 200 Joules, forcing you to puckering up.

Re: New Gauss Rifle
Bjørn, Tue Apr 25 2006, 09:56PM

There was a warning further up to stay on topic and since no one paid attention to it I will lock the thread. When Remus has a some new specific questions that is not answered in the HvWiki or in a simple search he can start a new thread.