18 replies to this topic

[FromAbove]

So it looks like I finally am able to unveil my new homemade. I thought I may as well jump on the acronym bandwagon and called it the BFG (Big Freakin’ Gun). My roommate is sleeping so no pics till tomorrow morning but I’ll do my best to describe it.

It’s powered by air pressure and is pumped up by 2 bicycle frame pumps mounted on the body with a tandem handle, making it doubly efficient. The primary chamber is 2-inch SCH40 PVC with ¼ inch threads coming out of both end caps. On the back are the two Schrader valves, which are called snifter valves (home hardware) and are connected with a ¼ inch brass tee to the chamber and a pressure gauge measuring the initial pressure. The threading through the end cap is reinforced internally with a rubber washer, metal washer, and length of ½ inch copper, which is sleeved onto the threaded ¼ inch steel pipe and is secured by a nut. As a precaution I poured a generous amount of epoxy into the end cap, sealing the washers and the seam between the steel washer and the copper pipe.

On the other side of the 14-inch pressure vessel is another steel threaded end cap that is connected to a ¼ inch pressure regulator that lowers the pressure to a much more usable pressure. From a 90-degree brass fitting goes to a male copper adapter that threads into an electronically actuated sprinkler valve. The valve controls the flow of air into the secondary (firing) chamber which is roughly 7 inches long made of 1-1/2 SCH40 PVC and has a 90 degree bend to utilise as little space as possible. The firing chamber is threaded onto a brass ¼ inch tee that connects to a second sprinkler valve that empties the firing chamber. Connected to the sprinkler valve is the bolt. The bolt’s movement is a little tricky to explain as it moves only an inch or so forward and back and rotates 180 degrees. The main idea for this is to have a somewhat gravity fed where the cartridge falls into the bolt from a rotary linear magazine (not connected to the gun but built) which holds 24 shells. The cartridge sits in the bolt that is then rotated 90 degrees and pushed forward to seal the faces of the shell. The shell is made of ½ inch copper with 2 copper couplers with a 1/8-inch recess on each side to allow for the shells to sleeve into ¾ inch aluminium tubing and provide a great seal and also allow enough play for the shells to fall into the handle, falling out the front of the handle. I can use CPVC shells with 2 copper couplers, which is lighter but the 5/8 inch FBR I have fits beautifully into ½ copper and loose fitting in ¾ inch aluminium. If I want to use micro Stefans I have CPVC and ½ FBR just in case. The barrel is fixed to the gun and is about 16 inches long, with a gator lock on the end. I made a silencer that adds another effective 10 inches to the barrel and does great to help muffle the massive thunk the gun makes.

There is so much I may have missed and left out, this is mainly just a rough description of my homemade. I’m just happy the fucker is finally built. I put the electrical wiring in tonight and have only test fired it a few times, but the velocity and power behind it is intense. I’ve left the air assembly as one working piece, and the barrel assembly another. I’m planning on making a paintball loser assembly and a large bore foam chucker that uses ½ inch foam pipe insulator and brass plumbing ma-jiggers (I forget the name) for shells. I will be using the plastic alternative shells that fit 3 pieces of ½ inch copper real well to make a shotgun round.

My fiancé is especially glad it's finished, she feels neglected when I spend so much time in her basement (I use her basement as my workshop).

So I'll get pics tomorrow afternoon.


-Riley

Edited by FromAbove, 25 April 2006 - 08:54 PM.

[FromAbove]

So since it is such a great day outside I got the chance to steal away from packing for a move and did some testing in the backyard. I tested the system to 120 psi and with crappy stefans (5/8 with 2-1.77 steel bb's) I'm getting a consistant flat trajectory of 125 feet@60 psi with a few feet of dart skip from about 2 feet off the ground (I was kneeling). The park across the street is busy today so hopefully by sunday I'll be able to get some maximum ranges tabulated. Accuracy and velocity is amazing, I plan on getting a reflex sight for this in the near future.

I took some more pics...

Snifter (Schrader) valves and pressure gauge.


Pressure regulator.


Rough trigger assembly.


Bolt opened, shell chambered.


Bolt closed, handle forward.


Bolt rotated into ejection port, shell coming through handle front.


Shell made of 1/2 inch copper and 2 copper couplers.


Barrel end, showing the gator lock.


16 inch silencer.



Edit: It seems as though I neglected to add the hotlinks to the pics for larger sizes and tried to add them with no luck, hope the pics are big enough.

Edited by FromAbove, 19 April 2006 - 05:48 PM.

[ShadowSniper]

I'm loving the look of this thing!
Excellent work man, just a few questions:
1. Where did you get the regulator? I've been looking for one to no avail.
2. Is the trigger/triggers just a power switch for the solenoids or is it something else?
3. Could you elaborate as to how the bolt/shell ejection thing works, I'm not really getting it.
4. How many shots can you get off from one tank?
5. How many pumps does it take to fill the tank back up?

Anyways, I thing this thing looks wicked and from the sounds of it performs great too. Good work!

[Black Wrath]

That thing looks ridiculous.

[KnightValor]

Whoa. I mean... whoa.


You really must've put some time into it, it looks very, very complex. Or at least hard to make... Whatever. It makes me think though... "Just build something simple, like a snap!"

Although, it seems to have paid off very, very well.

[davidbowie]

You really must've put some time into it, it looks very, very complex. Or at least hard to make... Whatever. It makes me think though... "Just build something simple, like a snap!"

Is that in reference to the Boltsniper.com topic? That was a different guy with a different "design" and no idea what he wanted to do.

This is indeed an awesome gun. If you went to the trouble of making a shell system, though, I want to see a magazine on that thing STAT!

[FromAbove]

Shadow loser,

1. Regulator is a regular air tool mini regulator found at my local Home depot.

2. The trigger is just a power switch, I was going to run a power switch and a momentary to actuate the pilot solenoid, but I wanted a simpler route.

3. I worked on a few ejector systems but really a gravity fed system is more reliable and requires less working pieces by nature. Simply put look at the pic of the shell. The shell falls into a slot which closes against the fixed barrel and the lip of the shell slides into the 3/4 aluminum. When the shells falls in I'll consider that 0 degrees rotation. When you push the handle forward it moves the bolt and seals the shell to the bolt and barrel. I cut a diagonal ridge which pushes the bolt forward while moving it 90 degrees down from the top. The way I made it I can also use my thumb with ease, which is what I intended. To eject the shell you simply pull the handle back to its original position and use your thumb and push the bolt rotating another 90 degrees. If you look at the pics I took one with the bolt at 0,90, 180 degrees, just look closely.

4. I got some information from DB, general primevil and others about sprinkler valves and they are amazing valves but require additional pressure to reset the valve (reseal the orifice) My hope was a semi-auto ability to use about 3 or 4 shots per pumping. The valves lose a lot of air resetting so right now I can get two shots per fill, depending on what my regulator is set at, but this far I'm pleased with the results.

5. The primary charging chamber is 14x2 inches plus the endcaps, plus the firing chamber. I intend to buy a C02 bike pump to get instant pressure and I have a set up for 2 frame pumps to be pumped in tandem but for functionality right now I'm using a full size frame pump. Anyways I digress, it takes roughly 30 pumps to reach 120 psi in both chambers, so obviously less pumps if the pressure is lower or if I filled only one chamber at a time, I've been testing so there is a great deal of cosmetic and finctional work still to be done.




Knight Valor,

It's not about simplicity, it's about that fucking crow. Ok long story short. It wasn't nerfing that got me into homemades it was the drive to kill the crow that would come around my house last summer when I was working 3 full time jobs and would crow at 7am on my days off... Only My Days Off! Needless to say that birds days are numbered. I also wanted something that I could war with at my University, hense the need for the reg.
Also the design took lots of time to come together because I eyeball for the most part and love to tinker to make things work right. I built this with a drill, dremel and scroll saw...plus a few other things obviously.




DAVID BOWIE!

Thank god someone reminded me, I forgot to post pics of the mag I built but not put on the gun yet. I'll post pics tomorrow. The mag is a 6 barrel rotating mass not unlike a minigun that holds 4 shells per pipe. The mag holds 24 with one in the chamber and is removable. The mag slides onto a plate that has a bolt that slides forward to allow for singular rounds to be put into the mag. Under that the shells slide from the mag through a small opening and into the chamber. It's like an upside down shotgun mag, without springs and the needless complication. I wanted something simple and effective after seeing Pineys and others linear magazines and seeing a rotary design in a real shotgun...made me want one of my own. It's simple because all you need to do is tip the gun forward while actuating the bolt and gravity slides the spent shell out of the gun and advances one into the chamber.
Shotgun Mag
Imagine this upside down, somewhat bull pup for weight distribution and having six barrels instead of four.

[FromAbove]

Pardon the double post, it’s been a few days and my posts have been huge so why not break it up a tad instead of one massive edit.

Anyways, I added the magazine onto the gun and decided to change the shells. Instead of two couplers and a 3-inch piece of 1/2-inch copper, I decided to shorten the shells to 1.5 inch CPVC with one copper coupler. I was planning on getting rid of the idea of using 5/8 Stefans but didn't know for sure till this weekend. So I sleeved 3/4 aluminium with 1/2 CPVC, the fit is snug, requiring only a bit of e-tape to make it secure. I made a batch of alternate shells and tested my magazine. Everything was built with the notion of weight, as my magazine would carry 6 feet of copper and 50 couplers in turn.

The utilization of CPVC lowered the weight and the length of the shells allowed me to almost double the amount of shells in the magazine. With the former shells I could carry 4 shells in 6 rows totalling 24 with one in the chamber for 25. Now I can carry 7 shells and one in the chamber for a grand total of 43!

I also did some range testing and dry firing and whatnot and this is what I found...

Using micro Stefans weighted with an 8-1/2 wood screw and nominal hot glue:

New tighter barrel (1/2 CPVC) and 1/2 CPVC shells, I was able to lower the working pressure of the regulator to 30 PSI from 60psi and am getting the same range of roughly 120 feet. The sleeved CPVC also increased the accuracy to the point that my gun can now support a scope if I wanted. I have been hitting a 2'x2' pizza box from 75 feet with a few shots to get the coordination right.

Since I lowered the regulator pressure, I am able to get a consistent 5 shots with minimal drop off. Both sprinkler valves use some precious are to reseal their orifices so the efficiency of the system is lacking. I could have used a ball valve to operate the lower chamber, but that would involve moving my hand from the handle and currently my hand never leaves the handle or trigger so it works out. I have also ordered a C02 bike pump from my local bike shop this morning, which will give instant pressurization.

I was able to range test this morning (it’s 3 degrees Celsius, but at least its not raining) and got a chance to get a maximum range…

I went to an old dirt cliff off a road outside of Peterborough and measured out a length of about 400 feet and stood back in 100-foot increments. If I saw a cloud of dust I scored a hit. Keep in mind I was not using typical Stefans, I was machine screws that weigh almost 5 grams and the foam served mainly as a sabot. I didn’t want to waste much time as I only had 5 of these heavy Stefans so I stood back at the 400-foot mark and put the pressure tank to a max 160 PSI (as high as my pump will go) and discharged both chambers at the same time. Again I was aiming for a pizza box and the little cloud of dust landed about 2.5 feet from my intended target. I was kneeling to steady the rifle about 2 feet off the ground and maybe had 5 degrees or so barrel lift from flat. There is little or no wind today which is great so I shot 4 more times and consistently hit the cliff with about 2-5 feet variance in accuracy (I don’t even have iron sights yet). I am calling the max effective range 400 feet.


So now that I have everything functional I’m going to keep perfecting things as time progresses. But I am extremely happy with the results. 43 round capacity, Semi-Auto firing, and Pump action. Plus the thing weighs 20 pounds dry; it is something I can lug around with relative ease, even with one hand because the balance worked out so well.

I’ll post updated pics soon…


-Riley.

Edited by FromAbove, 26 April 2006 - 11:25 AM.

[Meaker VI]

20 pounds? Man, they were complaining about a 15 pound gatling gun in Captain Slug's topic. That thing sounds vicious, I hope you acheive your aim of eliminating the crow with it. And not accidentally 41 passers-by, a mailman, and a garbage truck.

[z80]

Wow! That is one insane gun, I hope you make some type of guide for this monster.

[FromAbove]

Looking back at this topic, I write far too much. I suppose I'm just dying to talk about the long hours put into this thing.

Z80, I would love to write up something on the gun but these days I'm working 6 days a week, plus writing exams this week and summer school starts up next week so I am extremely busy. Hopefully by july I can have something worth sending into the NIC.

The weather was not going to hold up for long so I took some new pics of the gun with the mag, and I also took a short vid...loading 7 shells into the mag tube and running them through a dry fire.

Rough Layout

Tubular Rotating Magazine

Loading Bolt Closed

Loading Bolt Opened.

(Video)Dry-Firing of the Gun

There is still a lot of work needing to be done, making the reloading smoother and whatnot, I'll just keep plugging away.

-Riley

Edited by FromAbove, 26 April 2006 - 07:01 PM.

[Spartan064]

It...looks...beutiful. Good job, FromAbove, or Riley, or whoever.

[davidbowie]

That looks pretty cool. One question: what prevents more than one shell from loading? It would seem that opening the bolt (I'm assuming the bolt is a cylinder which covers a hole. I can't really tell from the pics) would allow shells to keep feeding continuously.

20 pounds? Man, they were complaining about a 15 pound gatling gun in Captain Slug's topic

I hate to be such a nitpick, but that was a 15 pound BATTERY. The real gun will weigh quite a bit more than that. Regardless, I'd rather put down my machismo for a while and have a gun that I can run around with.

[FromAbove]

That looks pretty cool. One question: what prevents more than one shell from loading? It would seem that opening the bolt (I'm assuming the bolt is a cylinder which covers a hole. I can't really tell from the pics) would allow shells to keep feeding continuously.

The bolt has room +/- 1/2 of an inch or so between the barrel and the rear sealing face of the bolt. When the gun it tipped forward like a stock class paintball marker the shell sits atop the bolt in a groove cut out for it, when the bolt is rotated to allow the shell to fall into the bolt, there is an odd chance that one shell will fall on top of the shell loaded in the bolt itself...however the second shell gets pushed aside by the bolt as it rotates, closing the bolt chamber and the shell is pushed up and is left sitting atop the closed chamber. This just took some careful sanding to get everything working correctly.

I am half thinking of taking the thing apart and taking some detailed pics of each component. Maybe next weekend, hell week starts tonight.

[chip tortellini]

Dude that thing is sweet!

[CaptainSlug]

20 pounds? Man, they were complaining about a 15 pound gatling gun in Captain Slug's topic.

That's because I have skinny arms.

[KirbySaysHi]

I noticed you were waiting for a CO2 pump from your local bike shop...

I tried one of those (if it's the same idea..), and the volume just isn't there in a 12 gram CO2 to fill up a larger air tank.

But maybe it will, ya never know.

Copy!

[flamebo388]

How the hell did I miss this, that thing is BEAST. Good luck on further improvements man, may the reaper live long and thrive.

[FromAbove]

It looks as though I am going back to the drawing board on the reaper. There were several areas of improvement, which I cannot deny.

First and foremost the weight and size is an issue. The damn thing is huge and unwieldy.

The design was primarily going to use 3-inch shells, therefore the bolt, bolt movement, lengths of specific parts all demonstrated this constraint. But now that 1.5 inch shells are used I am free to shorten these parts and make the reaper as I primarily intended, a Bull pup assault weapon.

I will be removing the secondary chamber and first valve because the semi-auto actuation it was meant to satisfy just was not air-efficient enough with the sprinkler valves using air to reseal their faces, twice for every shot. This change will cut weight and by using a momentary switch instead of a...um...non...momentary switch the shoot-reload-time should be greatly reduced and much more efficient in the end.

I also have a 16-inch barrel in a 36-inch gun. I see no problem in cutting that down to 12; retain accuracy with enough space for gas expansion.


In the end I do not want a 3 foot long, 20 pound monster, I want a 24 inch, 10 pound monster that would be much more ergonomic, while keeping the 43 round capacity and the means for chambering because it not only works, it looks so damn sweet.

I welcome ideas and hope to post a diagram sometime in the near future.