This is a theory thread.
-Sure.

Try it and tell us the results later.
(two interpretations)
-Ok, I'll shut up and not ask the community for help.
-When I try I will tell you the result.

I made a quick post when a person was working on an idea, and it made Galaxy613 say,"That makes sense!" and TRY it.
-I am looking for a response that makes me go "That makes sense!" and TRY it.

He came out with pretty good results (not verbatim instructions)
-How are the plans verbatim? "adj: "corresponding word for word to the original source or text: a verbatim record of the proceedings."

but he used my IDEA instead.
-I'm looking for these IDEAs.

If you are actually trying this, say that in your first post and say, "I would like suggestions in helping me do _____"
-I should have done this.

I apologize but I took some offense from this and the caps lock.

Kid Flash: It's one hole for 1 tank at a time, but yes I'm pretty worried about the seal. I can't find any 2ks and the big piece of plastic just serves as the pressure chambers. Air is actually released by the hole in front as the insides rotate.

Has anything like this ever been attempted?

I intend to build this in the near future but right now I'm very busy with summer school. I would like suggestions in helping me to improve this design or otherwise how to go about constructing it. Please don't refrain from saying "wow, this is a big failure waiting to happen."

Currently I'm going to find a large hunk of plastic for the internals and see if it's even within my price range. The outside will be made of pvc fittings and seals will be made with large rubber washers around the pressure chambers.



Is there a specific name for this type of thing? Searching "rotating valve" on google gives me useless information and this topic appears on the first page of results.

You're thinking too much.
Ompa used a paperclip at the top of the magazine to keep darts from flying out. It probably squishes the top dart a bit, but increase the surface area and the effect is minimal.

The NTS uses a breach where brass slides over the inner barrel (the opposite of the angel breach). The wings can simply pop over the outer brass when the breach is closed. You can also do this with a longshot.

200 mph = 293 fps
20 mph = ... 29 fps

My big snap at 220-240 fps easily clears 100', but foam balls do not have much mass to them and deal with much greater air resistance due to larger surface area. 75' is very believable.

You say that you get no pressure and that you hear no leaks, and for sure the pump is working.

Then where is the air going?

Here is the plunger I used in my big snap. It's similar to a standard plunger, but due to it's length it had to be rigid instead of floating. It was the lightest plunger I possibly get.


The old plunger looks smaller, but it weighs 3.6 oz vs 2.6 oz. Right now the sliding plunger doesn't seal as well as the gasket because I originally used a steel washer to keep the O ring in place and this severely scratched up the brass. When I replace the brass I could probably get just as good a seal.

There is very little friction between the O ring and the brass.

Once it's all sorted out I expect a good range boost.

Unfortunately I can't get velocity data anymore. The school suddenly woke up during my live presentation of the big snap and now they're no longer allowed on campus.

I relocated barrel on my Snap1b, losing some of the magazine in exchange for the pvc "tube." It gets pretty much the same range as before, but with 3 shot RSCB instead of 11 and it is 14 inches shorter.

I made it so it is relatively east to revert back, and I'm probably going to do this. 11 shots is just too awesome.

Pictures worth 100 words.
primed
still primed
inside



My plunger slides over the guiderod, greatly reducing mass and removing that pesky rod sticking out the back of your snap 1. It's made out of a X -> 0.5" bushing with a drilled out endcap as a catch and an O ring sandwiched between sch80 0.5" pvc to seal against the guiderod.

The guiderod is sealed at the end with plumbers goop.

With this setup you can easily recreate something similiar to Carrtoons Tec 9. Just remove the cotter pin, unseal the brass, and glue on a combination of brass and pvc as an outer stop.

Still need a way to make easier handles...eh, that's another day.

Have you ever considered a tee and a 45 degree elbow?

The Tee looks significantly cut down in your picture. I'd be worried about it snapping off.
Edit: I thought about it some more. My diagram may not be that significant for this case. I was probably thinking about using a huge 2" tee.

Some people have mentioned that their pet shops sell 9/16" petg. In the same place there should also be 1" petg. I've used it to make longer plunger tubes for my nightfinders and I'm pretty sure its the same stuff Kbarker used in his nightfinder rifle.

Splitlip, I appreciate your input, but I think you are overcomplicating things.

Allow me to restate my question and theory:


Does this really happen and waste energy? I do not have clear piping so I cannot be completely sure if the darts actually get moved.

The secondary question was, do people with RSCB barrels notice range decrease as they fire more darts, or do they stay concistent? As far as I've been lurking, I've seen people say the former, but my experiment showed the latter.

I would never expect anyone to copy my entire gun and environment. When I asked if anyone could confirm my findings I refered to the above questions.

If I gave that impression by listing gun details, I appologize. That was to give something to go against incase anyone else actually gets velocity data. I am using a big SNAP with probably double the normal spring power. If anyone could match my velocities with say, a nightfinder, I'd be extremely doubtful and ask how it was done.

Big SNAP with 11 shot breach loading RSCB magazine in the stock. It uses a 12" barrel with a detachable 8.5" extension.

The vertical handle feels comfy because I never hold it like a pistol.

Hello all.

I did a physics project on nerf guns. I tested the effect of RSCBbarrels on dart velocity using normal barrels as a control.
big SNAP data
photogates

Dart velocity did not gradually decrease as I fired more darts. In fact, velocity seemed go randomly go up and down after the first shot. However the gun also had inconsistent results using normal barrels, so I can't draw a direct conclusion other than "the plunger is so big that the deadspace filled by darts means nothing." But it still got me thinking about energy conservation.

My theory is that when you prime and maneuver the gun, darts shuffle around randomly inside the ammo tube. When shot level to the ground, the gun wastes random amounts of energy moving these darts to the back of the ammo tube before firing the dart. The gun would waste more energy if the darts were clumped at the base of the barrel than if they were at the back of the ammo tube.

This explains the problem Carbon had with his ball SNAP with an endcap follower here:
http://nerfhaven.com...ndpost&p=128410
The endcap is like a very heavy ball that the gun moves in addition to his first ball. The gun wasted more energy moving the endcap up than it did going through deadspace. In addition the last ball fires the hardest because the gun wastes more energy moving the extra balls in the ammo tube.

I unfortunately do not have time to take more data for my project, but I will test whether the gun really wastes energy moving loose darts by pointing the gun at a 45 degree angle up and down to clump the darts and compare the velocities.

Testing Conditions
-Big SNAP with CS-866 spring in addition to cut down SNAP spring (full spring is too long and warps when fully compressed)
-all barrels are 17/32 brass
-plunger volume ~17.7 cubic inches (2.125" ID and plunger travel 5")
-deadspace caused by 11 shot RSCB ~5 cubic inches
-darts are 2 inches long and weighted with 1/4" slingshot balls and a flat hotglue tip (pressed against a wet plate to harden)

Data was collected by mounting a photogate on the end of my barrel. The beam is about 1~ infront of the the barrel. The end of the gun was stabilized on a bar because the mass of the photogate causes the barrel to bend. The photogate had to be mounted on the barrel because recoil causes darts to go high and barely scrape or miss the beam entirely.

Can anyone confirm my findings? And would anyone else be willing to get solid velocity data using similar equipment? I'm especially curious how my snap compares to the +bow, which has less plunger volume but likely a much lighter plunger. I also suggest photogates as an alternative to range testing if your school has access to these tools.