Thursday, September 25, 2014

Koosh Dart (eBay/yutoys) Initial Test

My next step after trying out Voberry's darts was to revisit the well-known "koosh" dart.

The term "koosh" is never found in any listing or advertisement; it is an NIC nickname, due to the bristled impact surface (vaguely similar to a Koosh ball) as an alternative to the traditional air-filled dome.

If you are not familiar, these are more or less a third-generation stock type tip design, supposedly developed by the Chinese to solve the Elite's accuracy problems - and that they do.

However, there are two ongoing and widely reported quality problems with the final product darts made from these tips. One is undersize foam, which is not a big deal for flywheels but is no good for springers unless you want to go changing barrels to an uncommon small bore size just to accomodate them. The other is weak, inadequate or uncured tip glue, which leads to darts falling apart in use. Obviously, that is a critical issue that breaks the whole deal for any kind of HvZ or serious gaming.

Previously I have reported on the issues these darts have caused as a result. I had planned to buy koosh darts from common sellers, disassemble them and remount all the tips with the contact cement/CA method to explore the viability of such a process for average nerfers, since the accuracy benefits of the tip design are significant.

However, I encountered this thread on Reddit in which a user found one seller's darts to not have undersize foam. This seller is yutoys, on eBay. I ended up ordering from this seller.

Cost was $19.96 per 200 rounds, about 2 cents per round more expensive than Voberry's offering.

I received my order of darts in a little over a week. Shipped by China Post, this time with a working tracking number. As usual, they come in 10-round packets.

I can confirm the foam is not undersize on these. It is very similar to elite foam, definitely lower density and larger cell size than the Voberry stuff, and probably will hold up more like an elite than like a Voberry foam.

Here's where I was surprised. The assembly quality is not what is typically expected. The tip glue is well cured, if not terribly well applied and still far weaker than that used for other common darts. No tips arrive falling off with these. Tips are installed decently centered and square. Overall length is typical for koosh darts, about 2mm shorter than a dome tip elite. The foam length is slightly longer than an elite foam.

Chrono shoot

These are approximately 1.2g. Consistency was good across the board, although snap test numbers were lower than elites on the Tacmod.

In the process, note that compatibility with stock and typical springer barrels was verified, Rapidstrike reliability was verified, and the backstop was a wall a few feet behind the chronograph - and I did all the tests with the same 10 darts, straight out of the packet, with their factory glue holding the tips on. None of them failed during the test and I pulled out only one to be reglued before being sent out to the field (it was lacking a full application of glue under the tip).

Speaking of gluing tips to foam, I recommend the Remedy Metal contact cement/CA process:

Accuracy is very good for a stock type dart, that is all I will say at this point until I can develop a procedure and get numbers for common darts in the upcoming ammo roundup post.

I got some heat on Reddit by mentioning the state of my general opinion prior to the field test on the last ammo review, and for good reason. Apologies if the Voberry posts were a bit variable in conclusion between bench and field tests, so official recommendation will be made in the followup. For now, let's just leave it at these being the familiar "koosh" tip, with standard bore size foam and decent glue.

Saturday, September 20, 2014

Voberry Dart After-Action Report

These low-cost darts that I had previously described as "not competition grade" went to the USF stock class war today, and I am impressed. They may not be competition grade, but they are a hell of a product and certainly have their place, and I will likely buy more.

First of all, they shot perfectly fine. I was using the Tacmod, shooting 90-100fps with these. They are not at all inaccurate darts nor are the ballistics anything undesirable. I would consider them on par with lightly used Hasbro Elite Standard. Overall they are like shooting slightly more accurate Streamlines.

Second, reliability was perfect. I had a bit of an issue with J-code Elite not playing well with my mags this game, and this is not the first time. I don't think I am buying any more of that stuff - for a while I liked it, and it is true that modern J-code is not the disastrous Elite of 2012, but it does not have that great a reliability record and particularly when worn it can be a jam fest. These however... Forget malfunctions. Even the "competition grade" ZS Elite cannot measure up - the Voberry design is inherently a high-reliability design by the selection of a slick tip compound rather than a tacky one, and ZS Elite, lacks this inherent safety. You will not manage to make Voberry darts jam no matter how carelessly you load your mags.

Third, durability. The foam held up amazingly. All tips stayed tightly glued on, and the larger OD foam seems to reduce flywheel-related wear. These look new but they are not - they were just a few hours ago shot at some fellow Floridians. Fresh J-code would not look like this after a game of use!

Overall, based on the order I received, I highly recommend them for any use where maximum accuracy is not a primary consideration and you don't mind shooting a heavier dart. These would be a perfect dart for community ammo supplies, field rentals (Dart WarZ, that means you!) and HvZ service - cheap, reliable and built to last.

However, some reports of weak/inadequate tip glue from certain suppliers exist. I had zero tip glue problems with these darts - note the Amazon link in my original post from which I obtained them! Many eBay sellers are hawking Voberry-type darts and those seem to be the trouble source.

Elite CS Piston Mod

I recently did some maintenance on my Retal, and aside from all the dirt, I found one slight issue with the long term use of stock internals, which that the bolt eventually crushes the edges of the webbing inside the front of the piston head where it makes contact. Bit a design flaw if you ask me, it's an extremely small area to take the full spring force on priming and even with a stock spring the loading there is bound to cause plastic deformation of the edges of that webbing, and eventual trouble as that is a critical dimension.

In this instance, the catch engagement had started to get a bit less certain as the webbing collapsed and the bolt carrier hit the end of its travel.

I Devconned a disc of approximately 1/32" scrap ABS in there on top of the webbing. Problem solved. No more of the bolt end munching into that webbing and a little extra margin for catch engagement than stock.

I haven't chrono'd it yet, but the amount of added mass is very small and some dead volume (inside the webbed area) is also eliminated since I made sure it was sealed around the edges.

Thursday, September 11, 2014

Voberry Dart: Not competition grade.

A little less than a month ago, I was alerted to the appearance of a new low cost Chinese dart on Amazon, from a vendor called Voberry.

Link to product.

At first glance, the image and the "6.7cm" in the description led me to believe these were just more of those cheater-length hard plastic tipped junk darts, but reading the reviews posted on Amazon suggested otherwise, with claims that these were "slightly longer than" Elites and "durable" with no mention of tip glue problems, so I gave them a shot with a 100 round test batch.

Price wise, these are currently at $4.11 shipped per 50 rounds giving a cost of 8.22 cents per round, which is certainly excellent, and competitive with any of the other low-cost darts sold in bulk at the time (such as the well-known "koosh dart" and the "7.2 cm" knockoff Elites).

The seller I purchased from (JLTech1) seems to no longer stock these; however, 2 other sellers do.

The seller shipped via China Post. No functional tracking was provided. The package arrived in about 2 weeks.

Only a few deformed foams were found on opening the package which did recover.

As is standard for bulk darts from Asian vendors, they arrive in 10-round plastic packets.

The foam quality and density is excellent, probably superior to all Nerf brand foams of the modern era. These should last a good long time.

Of note is the foam OD, which is larger than typical .50 cal "stock" foams. I would guess these are a medium spring fit in .530 bore or so.

Fits in Nerf's stock barrels are unusually tight, but within optimal range for springers (whereas most "stock" foams are on the low end and tend to become a match or an overbore and thus underperforming and falling-out as soon as they wear out even a little).

The tip appears to be entirely constructed from a plasticized PVC compound of similar hardness to the thermoplastic elastomer used for genuine Elite tips. This is in common with clone Firefly streamline and elite sold by happyeverydaysales (HEDS) near the end of their dart sales.

The dome has much less tack than said rubber tips, however. This is beneficial for reliability and smooth feeding. These are excellent in magazine compatibility.

The tips are solidly installed on the foam with no dreaded glue faults.

A cross-section reveals the tip construction:

Like Elite tips, these are a 2-part design with a hollow cushioning/ballistic tip dome, vented by a small air hole to allow deflation on impact, with a dense "squib" of a second material forming the core and containing most of the mass.

In this case, the squib material appears to be identical to the dome, however, unlike a real Elite, but like an old-style Streamline.

The two appear to be mated by an overmold process as they are very well welded together and inseparable.

I cannot confirm the mass of these at the moment, but it feels (and shoots like, see chrono data) greater than that of a Streamline - perhaps 1.4g. Also, note the core length, shorter than a Streamline but about twice that of an Elite.

The overall length is very close to that of a Nerf brand full length streamline, not longer as some reviewers suggested.

As usual I put a bunch of these over the chrono. I do not have my full arsenal to test everything at the moment, so certain somewhat important concerns remain unaddressed (such as reliability in mag-fed springers) but at least Update: These have been tested with a Retal and a Stampede and ran fine suggesting no problems with magfed springer breech systems, and functionality of the barrel fit is confirmed with the troublesome Strongarm, which is a bit of a surprise.

Note how low the velocities are. That is consistent with a heavier projectile. I suspect these to be excessively heavy for stock class use. Consistency was OK, but given a heavier mass and lower velocities, I would not rate these well for consistency with a few bothersome numbers seen during this session. The Tacmod snap test numbers were also all over the place and I don't feel as confident with these as with Elite.

Preliminary accuracy observations were not impressive. These feel like Streamlines to shoot. It's like time traveling back to 2011. Elites, at least good ones, definitely have the edge in both time on target and accuracy.

Now here's where things go from OK to a bit sketchy.

Out of the 20 unused darts that I unwrapped for the test shoot, THREE of them came right out of the factory with the tip dome feeling SOLID.

Like it had been pumped full of hotglue by a noob, solid!

Visible through the vent hole was clear material, as used in the tip core...

Here you can see some of it through the split vent hole.

...And cutting one of these in half reveals the cause.

The tip core of this dart has been assembled incorrectly to the dome, apparently by some kind of overmolding process error. No air pocket is left. The weld is still solid as usual. Strange indeed.

Comparison to a normal tip.


Such darts are still perfectly functional (if a bit more painful), but do you want to use these where it counts if this is the state of quality control? I don't.

Also, here is a tip half removed from a dissected dart. The glue was easily broken and is applied only to the core, not under the dome. It seems to be the core length and barbs that hold it in place - and the fact that the glue is at least cured, unlike Koosh and many other poorly manufactured Chinese darts.

In the end, I have mixed feelings about these. The quality control and particularly accuracy problems, and the somewhat unhappy figures for velocity and flywheel snap response, mean I will not be buying more of these unless I discover something unknown when I take them to a game.

It is, however, nice to see:

  • A dart (any dart, even versus expensive ZS Elite!) with such good quality foam;
  • Another legitimate dart for under 10 cents a round;
  • A low cost bulk dart WITHOUT a major tip adhesive issue.
If all you need is a cheap dart that will last, these are an excellent choice, perhaps for loaner, backup or rental ammo. However, these are not quite there when it comes to serious gameplay, and ultimately it's a bit a shame because they come very close.

Pending: Magfed springer reliability test. Combat test in next game.

Also, next I will be giving koosh darts a good honest shot (with reglued tips).

Tuesday, September 9, 2014

Concept Demolisher Underslung Launcher Relocation

A quick one.

Stock Demmo:

Proposed launcher position change:

Original image credit: Prop Weapons Coop

The number one complaint about the Demolisher's launcher installation is that the overall system is very tall and ungainly. This is not necessarily inherent. The stock launcher location obviously is constrained by the flywheel cage and the desire to place it as far back as possible, as well as the need to accommodate the flange on some types of handguard sets of barrel extensions when installed on the twist-lock.

To that beef I add that there is no natural support hand position except on the ungainly launcher pump grip. The launcher blocks the front of the mag and magwell entirely.

The concept moves the launcher forward and upward, closer to the inner barrel and in front of the flywheel cage, theoretically remedying both the ergonomic and the aesthetic shortcomings. The twist-lock is rendered useless by the launcher barrel's proximity; but in practice I consider this twist-lock of zero practical use and would install a nice big tacticool flash hider instead. Also, the typical Hasbro cheek rails are taken out (likely entirely removed in an actual build, as in the Tacmod) which is similarly just fine as these rails' position renders them practically useless for lights.

Monday, September 8, 2014

RS Tacmod external charge connector

Seeing as there is no easy way to make a RS stock battery "user removable", I planned to add a connector for charging the pack in place from the start.

Here I used a surplus 5 pin DIN panel mount connector and a molded cable assembly that matched.

Any simple charge connector install will have battery voltage on it continuously, so choosing a connector that properly guards against short circuits is imperative. Generally, that means pin-based designs should have a female connector on the gun.

Also, if you are going to use your charge connector to supply power to anything external, be sure to use a connector rated for whatever current is involved.

Finally, you need the correct number of conductors to charge your battery. For nickel chemistries, this is 2, and you can use a cheap and small DC barrel jack (but only a barrel jack, not some audio connector such as a 3.5mm TRS, RCA or 1/4", as I have seen some nerfers use incorrectly for power).

For lithium-ion, regardless of what anyone else tells you about charging these, nowadays it is considered mandatory to balance charge, or at least use a charger that monitors individual cells. This requires 3 more wires than there are cells in series - you need 5 wires for a 2S pack. Go look at a lipo and note the total number of pins on both connectors - yes, do you need all of them. More about that later.

This is the connector installation in the receiver.

And the cable plugged in.

Remember what I said about needing access to every single wire coming out of a lipo (or other lithium-ion pack with multiple cells in series) in order to charge it properly?

A Li-ion balance charger typically has 2 separate connectors that are attached to the pack.

One is the balance tap connector, which has one wire for each interconnect between cells plus each free end of the series string - 3 wires for a 2S pack, 4 for a 3S, and so on - and these wires are supposed to terminate as close to the actual cell as possible. This is used to sense cell voltage as well as charge or discharge individual cells to balance the pack.

The other connector plugs into the pack's discharge leads and is used to pump charge current through the pack.

Note that this arrangement minimizes or eliminates the portion of the main charge current path that is shared with the balance connections. Wiring and interconnects have resistance, and when charge current is forced through resistances, voltages appear across those resistances. If these voltage drops are included in the cell voltages measured by the charger, they constitute errors. Even if we are talking about large power wires and Deans and the like that really don't have much resistance relative to the charger current, even small voltage errors are a big deal in Li-ion charging.

This is why balance connectors have "seemingly redundant" connections to the pack, namely the ones that duplicate the pack positive and negative leads.

When you install wiring for charging a Li-ion pack, it is important to maintain this separation, and not share wires - for example using 3 wires to charge a 2S and just cheating by hooking your innermost and outermost balance connections to the main leads at the charger.

That is however, what I did here. Go ahead and boo and hiss.

I found out my surplus cable has one pin unconnected and I needed this rig working now. That it does, but charging at too high current will give the charger fits, and balancing isn't perfect either. Moral of the story this is not just theory the RC people talk about with balance wiring!

This bad cable will be replaced and the wiring switched to use all 5 pins and separate balance wires in the near future. Hell, probably in the very near future, as the kludgeness of this thing grates on me.

Anyway, here's it charging.

As a footnote, charging LiPo while installed in something is strongly frowned on. If you use LiPo (and not LiFePO4, NiMH, or hybrid Li-ion like me) you should avoid this type of setup entirely.

Thursday, September 4, 2014

[Rant] Human organization, discipline, and trust

Let's talk about something that annoys me: careless human HvZ players who mess up other players' game.

Recently, at Waterloo's first invitational, I went on missions with several different groups of humans, with varying levels of organization, varying levels of human reliability, and, as a result, dramatically varying levels of success. Case in point: when the Windsor group secured and completed a puzzle in a small atrium, they did so with no losses and in good time - the zombies pestered us heavily, but that's all they could do as there were people watching all of the entrances at all times - versus a ragtag group milling about and failing to find a bottle in a different atrium, with several people being lost to a few opportunistic zombies.

There are a few specific people whose carelessness has inspired this rant. I'm not going to name names but, if by any chance any of you are reading this, you know who you are.

Let's clarify one thing right now: I'm not saying that there isn't a place for goofing off in HvZ, or that the serious/"milsim" approach to play is the only right approach. In fact, the opposite is true - HvZ is a game. We play it because it is fun. Approaches to the game cover the full spectrum from the immersive and serious to the goofy and careless. There is most certainly a place for goofing off and for being reckless in HvZ.

What I am saying is that group operations are not that place.

Waterloo: Pictures!

As it turns out, someone brought a camera to Waterloo's recent game - and they took some really good pictures. Link.

I'm the person in the orange shirt with two Stryfes; you can see me getting stomped by the tank, and a sockwhip-user coming to my aid just a little too late (mostly my fault; I really should have turned and ran, or noticed the armbands sooner and switched to socks).

Those duck tape magazine holders that you can see me wearing deserve special mention. I've been experimenting with different ways to make duck tape magazine holders for a while now, and I've almost reached the stage where most of my dissatisfaction comes from the design of the magazine itself rather than the holder. Duck tape holders are fairly quick to make - the ones that you see me wearing were made the night and morning before the game - and will be the subject of a future post.

More pictures of the magazine holders can be found here. Credit goes to . . . um, darn it, I didn't get the name of the person who took those pictures for me. (If you're reading this, please speak up in the comments. )

The blue bag was supposed to be a dump pouch, but it didn't work as planned. Magazines didn't fall out of it when I tested it by jumping around the house, but they did fall out during the game. This goes to show that HvZ is very, very unforgiving of cut corners in terms of equipment security.