11 replies to this topic

[Carbon]

I showed a pic of the SNAP-2 in the homebrew thread a while ago. The goals for the SNAP-2 were a side-pull charging system, and clip feed. Here's the functionally finished gun - still needs to be painted and have a few additional parts added to it, but all systems are working.



Here's the clip loading system:



I make no claims to the originality of the system: it's pretty much Renegade's R-Clip system, with a few subtle changes. Mainly, I ground down a washer, and seated it in the joint of a OVC coupler, and then added a rubber washer above that.



The benefit of this is that when the bolt is pulled back, the end of the brass is biting into rubber, making an airtight seal - no air loss, period. The airflow reduction has also caused a serious increase in the velocity of air coming from the plunger - I have yet to actually test, but darts seem to be hitting hard

This is the bolt:



The barrel itself is 17/32" brass. I only used 9/16" brass down by the breech, and another ring of it higher up to keep things centered. I used an endcap at the end of it all to keep the bolt in place. As luck would have it, using a tube cutter on brass curves in the end, making a great fit. The barrel itself starts a quarter inch from the end of the bolt.



This is because I was having problems with the dart end getting caught under the barrel, causing a misfire. Since the 9/16" is considerably wider than my stefans, it solves that problem.

Here's the clip:



It's a cassette case that I cut down to the width of my darts, and then hinged. Yes, the hinge I used is stinkin' huge, but it was the only one I had around late last night. I kept the original tape hinge on it, because it acts as a door catch, keeps it from swinging all the way open.

Loads with gravity feed:



The brown is a chunk of dowel to give the stack just a bit of weight. I can load up 7 darts, six of which can fire. This is a good thing: that last dart keeps the dowel from chambering, so I don't accidentally fire somthing a bit more painful than foam.

There's still a lot I'd like to do: a spring return on the bolt would make life easier, so I don't have to pull back against it. I need a couple of parts to finish the stock. Testing to determine my optimal barrel length would be good. Some reinforcement by the clip is necessary, it's just hotglued on. I'll need to become more proficient in my dartmaking; this gun really shows when a dart is off balance. Oh, and sights - it's accurate enough that they'd be a lot of fun. If the washer gave me as much additional range as I think it did, this could be a damn fine sharpshooter gun. As it is now, I enjoy plinking at the little target that came with my Nite Finder.

Edited by Carbon, 29 April 2007 - 08:52 PM.

[davidbowie]

Excellent work!

That's a clever way to load the clip. With my hopper, I find that dropping darts in the top lets them tumble and end up the wrong way.

Is there any specific reason for the grip being the way it is? It adds a little heft to the look, which is good, but why not just replicate the back grip?

[Carbon]

Thanks. Renegade used pretty much the same thing for loading, except that he used a VHS-C case. I just did a variant on his work.

You mean the foregrip? Yeah. First, let it be said that I'm not sold on that part right now....I'm gonna work on it, see if I can slim it down. It's a little "wobble" right now, it needs more guides. That being said, I used PVC and fittings because I wanted a tough joint, not using any glue. I didn't trust a hotglue grip to survive against a back and forth action. Besides, this grip could be assembled in about two minutes with parts from my PVC bin. Functional...but not finished.

[nerfer34]

That thing is nice! What are the ranges?

[Carbon]

That thing is nice! What are the ranges?

Before I added the airflow washer, I was getting about 65' flat. With that breech system in, though, I seem to be getting harder hitting darts, more velocity. Some of my stefans have been breaking on imapct... I don't want to speculate, though, I'll test and measure soon.

[davidbowie]

To strengthen the foregrip, you should cut a brace out of wood with curves on each side to fit the pipes, and put a hoseclamp around the whole thing to keep it together. It's makes things a whole lot sturdier.

Another thing you could do is buy a 1 1/4" tee or wye preferably with a smaller branch, and cut off the side without the branch coming out. Then use two hoseclamps to secure it on the plunger tube. You can stick your foregrip in the branch. This is the foregrip I plan to use.

[Carbon]

Oh, I finally get what you're seeing....the front grip is the way it is because it moves back and forth. It's connected to the front of the gun because that's what moves the bolt for loading.

EDIT: Just did an unscientific, one-shot-down-the-hallway range test.

Measured result: 74.5 feet, flat, fired from chest height.

Edited by Carbon, 13 February 2006 - 12:25 AM.

[davidbowie]

In that case, try hacking off the belled end from a section of 1/2" pipe (the handle is 1/2", right?), and putting it over that long shaft, then building the first brace I was talking about around the "sleeve" instead of directly around the shaft. That way it can still move, but it will wobble a lot less.

[WratH]

An idea to make the action one fluid movement...

You can probably get the gist of it, ask if not.

[Carbon]

Thanks, wrath, I've been trying to sketch an illustration of a slide system that could both charge the plunger and cycle the breech....nicely shown. The challenge with it is the differing amounts of travel needed - four or five inches to charge the plunger, but only one and a half to load. It'll involve sliding rods and stop points on those rods. I definitely want to move from the big honking handle I have right now to something like what you have there...thanks for the illustration.

[Starbuck]

I like it. I've got a replica Sten on the way, but my mag is mounted on the side and is removeable.

If you'd like an upgrade on the magazine, PM me. I can help you build one with a spring so you don't have to mount it atop and it's removeable. This cuts down on the mag being in your line of sight and is much easier to negotiate.

[Carbon]

SNAP-2 improvements, to the breech slider:



I cut out a slot on the bottom of the PVC housing, and placed the smallest hose clamp I could find in the slot. I then slid the barrel/bolt assembly through the PVC and clamp. The slot is as long as the action, and the clamp serves as a stop for the barrel. The only gotcha is that it's very easy to overtighten the clamp and dimple the barrel. I have a slight dent, but it doesn't seem to affect ranges at all (second test yielded 70 feet). So the big handle is gone; I just need to install some kind of handle/sheath to the clamp to make for easier loading. I also don't have to pull back on the loading handle to keep a good seal anymore....the spring takes care of that nicely.

Spring loaded magazines are hopefully coming soon, so I can have the reload lever on the top, and the clip on the bottom. What's nice is that the entire system is still modular. I could install it on the SNAP-1 with a barrel swap if I wanted. Hoping to keep it that way.

I also discovered that part of my misfire problem (where the dart smushes underneath the end of the barrel, trapping it) is because I haven't been cooking my darts long enough. I was gonna try and shape some of my darts for better feeding over a lighter, but as I passed the dart over the flame, I watched as they smoothed out and shrank. Duh. So I'm gonna toss them all in the dryer and hope for the best. (I've been using a hairdryer for 3 minutes...makes 'em straight, but doesn't make them smaller). I tried a magazine cycle with five erratically shrunk-by-lighter darts, and only had one misfeed. SHould be a lot more consistent when my darts are smaller and...consistent.

Edited by Carbon, 29 April 2007 - 08:52 PM.