Making an Airsoft Close-Quarters Carbine

About a month ago at an Airsoft game, I was trying to clean my friend's Airsoft pistol, and accidentally disemboweled it. Don't ask.

It was only a slightly leaky 35$ pistol that he had had for a while, so he wasn't really bummed and said I could take it and fix it, and If I couldn't fix it, not a problem.

Well, It took me about five minutes to fix.

Later on, I was searching Airsoft stuff online, and found pictures of converted pistol carbines. I have wanted one for a while, but the price and mediocre reviews have been kind of a put-off.

This project is for someone who has a good understanding of PVC heat-forming, so if you don't know how to do this, I would check out one of these Instructables, especially the first one.

https://www.instructables.com/id/PVC-Its-Great-for-Inventions/

https://www.instructables.com/id/PVC-Practice-Knives/

Those give basic info on PVC working and projects.
This build will be detailed in a basic fashion, in order to give you flexibility in how you make your design, and allow for any structural differences in your base pistol. Note that this design only works with non-blowback solid slide pistols.

Step 1: Get Inspired, Take Stock of Ingredients

First I considered the intended base pistol.

It is a Crossman C11 Airsoft pistol, with the following stats:

15 round stick magazine
true semiauto capability
accurate to a range of about 40 feet
contains the 12 gram CO2 cartridge in the handle separate from the magazine
has the mag release on the left side
the slide switch safety is on the right side
front blade and rear notch non-adjustable sights
shoots about 100 rounds per cartridge
is non-blowback
is very loud
the handgrip slides straight backwards to expose the CO2 loading slot.
Unthreaded muzzle
fairly small
magazines take a little while to reload, but are very cheap
fake forward mounting rail below muzzle (will not fit RIS or Weaver attachments, basically for show)

That's about all the trivia I can come up with at this point.

Next, I summarized what I wanted from the completed conversion:

indestructible
must not cost more than the original cost of the gun (approx. $30 US)
retains all original functions of the gun
easy to break down, preferably by hand, at most with a little multitool or something.
small and pointable
accepts standard attachments
actually helps to improve accuracy
low profile
not awkward, I.E. no sticking out parts to catch on gear, trees, etc.
possible integrated silencer
Generally looks good enough to not make me look like a total tool using it.

I worked with some professional research (Read: google image search) to find a basic idea of what I wanted.

I then sketched up some basic designs, but those were unfortunately lost in the Great Workshop Rearrange of February 2012. No big deal, they were overcomplicated, and once I got to work, the gun practically built itself, coming out much different, and better, than the sketches.

Step 2: Choose Building Materials

This is a very open ended build if you are using this Instructable as a source of inspiration rather than exact directions.

If you have access to a laser cutter, CNC machine, or other generally badass custom fabrication tools, you probably have come up with your own base design as you read this. Go wild, as I sit here in jealousy.

For the rest of us, there are still may options. You can make the carbine with PVC using fittings instead of heat-shaping. You can use wood, MDF, acrylic, whatever. To cut sheet stock I recommend using a Dremel rotary tool with a cutting bit. I say again, go crazy on the design, please, I would love to see your ideas. If you have none, but still plan to make your own, here are a few ideas:

If you use nested pipes or layered sheets of materials you can make an adjustable stock.
Hack parts off of older or broken guns if you want a more pro look.
Keep it light
Keep in mind that to make it so you can look down sights without having to jack up your sights, you need to add a bend in your stock.
Research real gun conversions!
Gut an old Nerf gun, if you are really out of ideas.

Ok, all that said, I decided to use heat- formed PVC pipe because it's cheap, strong, easy to work, and I have the materials and experience to do it.

Step 3: Tools

There are too many little tools I used for this to list them all, I just grabbed what I needed in my shop, but here is a list of suggested and required tools if you choose to build this gun like I did with PVC.

Heat gun or torch to heat the pipe
Some kind of saw to cut it, I varied between a reciprocating saw and a rotary blade on a power drill.
Vise or clamps with a wide clamp face to flatten heated PVC.
marker and ruler to measure and mark cuts.
File or other abrasive tool, I used a rasp bit in a power drill
Various drill bits
Rivets, washers, and rivet gun
Screws and screwdriver
Knife to trim flash on cuts, cut foam, etc.
Rotary tool with sanding drum to smooth rough edges more cleanly than a file.
A well-ventilated workspace is a must. I do all my PVC heating and forming outside in the open air.

Anything else you need can probably be rustled up in a basic maker environment. You could even make this with no electricity, if you have hand tools and patience.

Step 4: Make a List, Get What You Need

For the final build I used:

1/2 inch PVC- about two feet
1 inch PVC- about a foot and a half
1 1/2 inch PVC- about 5 feet, in case you mess up.
A flat endcap for the 1 1/2 inch PVC
Various rivets and backing plates for them
a piece of spare EVA foam, you could use the sole from a dollar pair of flip-flops, it's the same material
an 8-inch piece of modified RIS rail I stole from an old broken cheap M14 Airsoft gun
Four small screws
Krylon plastic primer, and camouflage base colors spray paint

All of this that I didn't already have came out to a grand total of $21.65 (US) at Ace Hardware

Step 5: Part One: Build the Integrated Silencer (NOT!)

My original plan was to build an integrated silencer onto the front to quiet it a bit. It is possible to silence CO2 guns a bit, because they lack many moving parts. I had a nice silencer designed and built, but after it was built and I shot it for a few magazines, the internal baffle were knocked out by the force of the escaping gas. I suppose they would have stayed better had I used something tougher than Krazy glue to sick them in. Anyway, they broke out, and the gun still looks like it has a silencer, however, it has the opposite effect.

Now when I shoot it it sounds much louder and sharper, and is way more fun and intimidating. In a small enclosed space the shots scare the heck out of people if they aren't expecting them. I like this effect better than the suppressed pop of a silencer.

Anyway, here is how to make the forward "silencer" of the gun, minus the labor intensive and annoying part of putting in the silencing baffles and drilling the holes in the inner pipe.

These mini-steps all correspond to the pictures in order.

Measure a roughly 7 inch piece of 1/2 inch pipe. Cut it to length, then cement a flat end cap onto one end. Let it cure for a bit, you should only have to wait an hour for it to cure to handling strength.
Measure a length of one inch pipe the same length of the exposed 1/2 inch pipe as shown. Cut it to length, then mark a straight line for a few inches along the pipe on one end.
Drill three holes that fit your rivet size closely along this line at regular spacing.
Drill a hole of the same size in the 1/2 inch pipe that matches the hole in the 1 inch pipe as shown.
put the 1/2 inch in the 1 inch pipe, line up the holes, and rivet.
Drill the next two holes through the 1/2 inch pipe the rest of the way using the holes in the 1 inch pipe as a guide. make sure you only go through one wall of the 1/2 inch pipe, it is easy to over-drill.
Rivet the last two holes. At this point you are done with the "loudener" attachment.

NOTES:

Use the shortest rivets you can in this step, that will still hold the parts together tightly. The bb goes through here, so you need to leave clearance for it! I think I used 3/8 rivets, but do some practice runs before you rivet the final piece. It is very hard to drill out rivets in PVC, so don't mess up!
Remember that you will not be able to use backer plates on these rivets due to clearance issues and the sheer pain of getting them into the pipe. Don't even bother.
This is how to build a sound magnifier, essentially. You can drill holes in the inner 1/2 inch pipe, the 1 inch pipe, add foam or cloth, seal the silencer, add sound baffles, whatever you want to do to change, increase, or suppress the sound. As long as it basically looks like the final silencer attachment it will work in this design.

Okay, on to the next step, in which you get to start heat-forming!

Step 6: Mounting Silencer

This is the simplest and strongest way to mount the silencer that I could come up with. It does involve drilling into the gun, but after looking at the donor pistol inside and out I saw that where I put these screws would not damage the gun other than four small holes into some solid body pieces. If you are using a different type of gun than I am, be 100% sure your screw locations will work like mine did.

Okay, as above, mini-steps correspond to pictures in the same order.

Cut a 5 inch piece of 1 inch pipe
Mark the piece with guidelines as shown in the second picture
Cut along the lines like in the third picture
Heat the plastic and bend the sides up, as shown in picture four. I bent them up roughly by hand first, then heated and clamped the whole side to make it straight.
Smooth the edges to make it smoother and generally better
slide it onto the front of the gun as shown, make any last minute adjustments, then drill pilot holes and screw it on with shallow screws.
Cut a 1 1/2 inch long piece of 1 inch pipe. In the picture I cut two, but ignore that and only use one, because that is all you need.
Cut a slot in the side of the short pipe piece.
Heat it and flatten it into a flat plate as shown
Cut the piece into two 1 inch by 1 1/2 inch rectangles. Smooth the edges down.
Rivet two plates to the gun assembly as shown in picture 13
Place the silencer and rivet it in place as shown in picture 14.
You are now done with the forward assembly of the gun.

NOTES:

I used some Sugru to seal the space between the tip of the gun and the "silencer."
After building this part, I found that the space underneath the silencer, between the bottom of the silencer and the mounting bracket, was the perfect size to store an extra 12 Gram CO2 cartridge. Pretty handy. I have yet to utilize this space though, since the gun is so CO2 efficient.

Step 7: Building the Body/stock

I decided to make the stock/body all one piece, to simplify everything. This piece slides over the body of the gun, and is held in place by friction, with no pins or clamps, so the gun can be taken down into two pieces by pulling the body/stock off.

Steps correspond to pictures when indicated.

Get a long length of 1 1/2 inch pipe, like three or four feet.
set it on top of the gun as shown, from the edge of the silencer cap back. Mark the length of the gun. NOTE: pull out the handle cover, and measure the gun that way. I forgot to do that, so I had to go back and cut a slot to give it room to move. Making the mark farther than it needs to be is no problem, but there must be at least enough room to fit the handle cover when it is slid out.
measure the width of the gun on the silencer mounting bracket, and mark it directly on the ruler (picture 2)
Transfer that measurement to the end of the pipe as shown in picture 3.
Mark on the pipe from the gun length mark to the two width marks, as shown in picture 4
Cut out a slot along those lines, like in picture 5
Slide the large pipe over the gun in the slot, as shown in picture 6. Note that in picture 6 there is not enough room for the handle cover to slide. It should be able to extend fully. If not, cut out more pipe until it looks more like picture 7.
Note the location of the safety, which is covered by the larger pipe. Mark a cut out as shown in picture 8, and cut it out like in picture 9.
Mark the end corners of the slot in the large pipe like in picture 10. They need to be cut off to make it much easier to slide onto the gun. Cut them off so it looks like picture 11. Then round them off with a file or something.
You may have noticed that the sites make sliding the large pipe on hard or impossible. I simply cut them off. IT really doesn't affect the performance of the pistol, since aiming it relies on more of a point-and shoot reflex than actually sighting. Pictures 12 and 13 show the sights and their removal, in case you can't figure it out. A file works fine.

NOTES:

It helps to smooth all cuts out, it makes the final product look way better.

The width of the slot is very important! Too tight and it is almost impossible to get together, too loose, and it wobbles and generally sucks. If your slot is too tight, shave the sides down bit by bit until you can slide the pipe over the gun easily, but it still clamps itself on their tightly. If it is too loose, cut it off and start over. That's why I suggested that you use a longer piece than you need.

Step 8: Shaping the Stock

As with any gun that has a shoulder stock, this gun needs a slanted stock to allow you to aim down the sights and improve the comfort and pointability of the gun. You could conceivably make a straight stock, than jack the sights up on riser rails so you could see down them, but that is awkward and ruins the gun's low profile and would expand your body silhouette, leaving you more open to being hit because your head sticks up farther. I opted to heat-bend the stock in one spot to allow for down-the sights aiming, then cut a chunk out of the stock to give more room for aiming comfortably. I originally planned to put a cheek pad in the space cut into the stock, but then decided against it because once I smoothed out the edges, it was comfortable enough, and the cheek pad kind of got in the way.

With out further ado, the steps!

So, with the large pipe slid over the gun, make a mark at where the end of the gun is with the handle cover closed.
Go about an inch back past that line, heat the pipe, and bend it down about ten degrees. mask sure the bend is straight down and does not tilt to one side or another. Let it cool completely. Refer to picture 1.
Slide the gun into the pipe, and notice that on the bend, the edges of the slot have bent over into the path of the handle cover. File those edges flat so the handle cover can move again. Refer to picture 2
Now, bring the gun up to your shoulder as best you can with the pipe in the way. Mark the distance from the bend to your shoulder. Mark the pipe at that length as shown in picture 3. my stock length came out to about 12 inches. It doesn't have to be perfect. If you are unsure, mark it long, then cut it down until it seems comfortable.
Cut the pipe on the mark like in picture 4.
The gun is technically useable at this point, but ugly and uncomfortable. Try it out a bit.
After you finish pointing it around and looking stupid, (see pictures 6 & 7) mark out a rectangle on the stock as shown in picture 8.
Cut it out as in picture 9.
Smooth the edges like in picture 11. This decreases the vertical space the stock takes up, and lets you aim easier.
Get a flat cap that fits on the end of the 1 1/2 pipe, like picture 12.
Get a piece of 1 inch pipe about 5 inches long or so, and heat flatten it into a double thick sheet, like picture 13.
Rivet the sheet onto the cap as shown. Picture 14.
Rivet the cap onto the back of the gun as shown. Picture 15.
Round out the ends of the stock as shown. Picture 16.
The gun is now structurally finished.

Step 9: Done, Painting and Improvements, Final Discussion

The gun is done!

Of course, it is still all rough, and has heat marks all over it.

At this point I also added a rail set from an old broken M14, a foam pad on the butt-plate, and an angled grip inspired by the grip in picture 2.

You will notice there are no sights. I was totally planning on adding them, but then I realized that one can look down the slot under the rail, and that makes a great sight.

I primed the gun with Krylon Fusion grey primer, then went over that with Krylon camouflage black and light Olive drab.

As you can see in picture 3, the gun is about 2 feet, three inches long.

Picture 4 shows the two separate parts.

The gun can easily be aimed when when wearing high-profile goggles like in picture 5.

As far as on the field performance goes, the gun did very well. Final judgement:

Pros:

Super small and maneuverable
Much more accurate than I thought with .20 gram ammo. I was hitting people at about 25 yards with only three or four shots. Due to the cheapness of the base pistol, you can use .12 gram ammo to boost strength at the cost of accuracy.
Fits to your body perfectly, probably one of the most comfortable small guns I have ever used
Loud and intimidating.
Light enough to be fired one handed.
Aiming is really easy. Goggles never get in the way, and target acquisition is pretty much instant.

Cons:

Never enough magazines. I can empty this thing in about two seconds, and I only have one magazine for it. I have heard you can buy C11 mags at Walmart though, more word on that later.
A little awkward to carry on a sling
The way it is built, one kind of forgets that it is still really just a cheap pistol. I kept forgetting and unloading at someone, only to realize that there was no way in hell I could hit them.

Overall, this was a good project. I will update it in the future with more in-action pics of the gun, as well as some better pictures of the finished product. At this point, I think I will leave the gun as-is, although I might do a digital-camo job on it at some point.

I am sure I left out some important details. If you catch any errors, need help, have suggestions, or any other input, please comment! If anyone builds this and shows me some pictures, they will get a patch.

Have fun and safe shooting.
Ilpug