Concept RS Tactical

If there is one most significant hole in my armory right now, that would have to be a basic, no-frills, rifle version of the RS.

It's not so much that I didn't have such a configuration at any point. In fact, I have had many such RS through my hands. They just "didn't stick". 

Why?

It's not that they aren't useful. What I have figured out is that the cause is...

The damn stock battery box. 

That has to be my most hated feature of the stock RS. Not that a big battery box isn't handy; it opens up a lot of battery options for internal, clean installation without a specific mod to accomodate each. Rather, it is the placement and dimensions of this thing that get on my nerves.

So this is going to be a post about casemodding ideas, more or less. See the old test mule:

The RS is such a nice, original, futuristic assault rifle design... WELL it would be, if not for that tumor growing in the handguards. The corners dig into my support hand. It's the widest point of the gun. Right up front. It just ruins the streamlining and proportions and makes it feel so clunky.

One of the reasons I have favored underslinging something is that without the integration there, the bulk doesn't vanish. When you have an externally stock RS, the handling is just out of line with its functionality, IMO. And I had one hell of a time thinking of how best to remove that bulk, since the battery box is so designed into the gun and the flywheel system has its own space requirements to worry about. "Just cut it off" is NOT an answer.

Finally, the idea of weapons standardization came up within Gators HvZ 501st, between me, CT-0268 (the squadmate who came up with the trigger VFG for the RapidSwarms) and the CO. That spurred things along and soon I was envisioning a "Tactical Model" of the RS to be one of our service rifles. So here goes:

 

 Start with a commercial RS.

I like to use a low-res image to mockup my mods. The pixels give me a nice grid for editing and aligning, and make quick manual changes blend into the overall appearance.

 

 This is what you have after whacking the offending features off the receiver and shrouds. Note that the AFG-style foregrip got nailed as well - because it's too damn low. And too wide. It can't be blended into a rework without looking noobish.

 

And here we've reconstructed a bit along the clean, chamfered, Stampedish lines of the existing receiver, then slapped an accessory rail on there. Starting to look a bit more proportionate.

 

The new sweet curved magwell grip is fabricated to match up with the lines of the shroud mods and rail. A few countersunk flathead screws would go in these parts for structural integrity and to replace some screw bosses which were cut off along with the bulky crap.

 

We're running 180 motors, so the side rail goes away and a cover plate guards the terminals and offers ventilation. The other stock side rail also goes away, since it is too short and too far back for practical use i.e. a light (a shadow would be cast by the barrel), and I dislike Hasbro's placement and aesthetics of these rails on both this and the Stampede.

 

Bodywork is smoothed, and an optional cosmetic flash hider (see: the one in the Oblivion prop build) is installed in place of the useless twist-lock for maximum tacticoolness.

This gun is to serve several purposes: act as a prototype for the physical build to be used by the squad in order to test the ergonomics, and be my next primary to supplement the RapidSwarm. As such, it will run a 3S stick battery located in the stock and most likely be a testbed for the Xtreme PRO 180 motor on flywheels and pusher. Expect a progress post soon.

[Mod] Swarmfire AR Delete and Flow Improvement

This is news from 2011, but I figured I would post some of the details of proper AR removal and a no-brainer flow fix for the Swarmy since these items are one of those things. You know, always overlooked, sometimes dismissed, sometimes misunderstood.

Start with the PT/AR/cylinder seal assembly. Note that the seal plate is a sort of cap, which is fit into a socket on the PT sort of like a pipe fitting. It is glued with CA glue.

Now, instinct may tell some of you to apply heat. Don't do that. No boiling. Too much risk of warping the seal plate or weakening the glue under the gasket.

Find a knife with a suitably thin and pointed blade (I use my old Swiss Army knife) and very carefully work around the entire circumference of the seal head until it can be broken loose. Try not to crack, damage or expand the socket too much.

Remove and discard the AR poppet and spring.

 

And here you have the seal plate. Note that the ports are almost entirely occluded by a plastic web that was used to guide the AR poppet "fingers".

 

And this is the most critical step, which is painfully obvious but frequently omitted for no discernable reason: Remove the webbing from the ports all the way to the edges. It is of absolute importance that you do not damage the black EVA foam gasket, or the underlying plastic of the seal plate, while doing this!

 

That's better.

Now, you must reinstall the seal plate on the PT. I use Devcon here, of course, but this is a low stress job and anything that can fill gaps and seal the assembly will work. Orient it correctly (match the oblong vent hole on the seal plate and the PT socket) and glue it in, making sure it is fully seated and the vent hole is plugged completely. Wipe all excess adhesive off the exterior and let cure.

 

Now you can test the cylinder seal install for leaks. Find the plunger, take the O-ring off, clean everything meticulously as if you were doing regular maintenance on the gun, reinstall and lube up the O-ring. I recommend white lithium grease for this seal. Run it in and out of the PT a few times to distribute the lubricant.

Note that you should NEVER put anything under the O-ring in an effort to "improve" the seal, and unless the ring is worn out, you do not need a new one.

Now you can press the seal head firmly against a smooth flat surface and give the plunger a quick push down (quick, so as to seat the floating O-ring seal). It should hit springy pneumatic resistance and if you keep pushing on it, nothing should be hissing and it shouldn't be rapidly collapsing. There should be practically zero friction from the O-ring seal. If you do not have trouble to chase here, you can proceed with the rest of the Swarmfire build. Be sure to consider the reliability mods particularly if you are going to run a high ROF or are an HvZ player, and select a worthwhile spring such as the OMW 8 kg.

Don't forget to NEVER install a plunger impact pad on Swarmfires, since the plunger does not impact the PT. The plunger's travel is stopped by the lug on the rear end of the rod and its matching track in the receiver. Most attempts (i.e. SGNerf et al.) at Swarmfire impact pads most likely don't do anything because the pad never touches the PT. If you use a thick enough pad to hit the PT at any point (like I did as a noob), you will cause major reliability problems, since the PT is free to travel forward and push on the cylinder causing excessive friction.

[Tech] The Devcon Tenets: Methacrylate plastic welding adhesives

There are very few tools and materials that have reached the level of "indispensable" for my work in this hobby, but one of the few on that list would have to be the methacrylate 2-part structural adhesives often known as "plastic welders", "plastic bonders" or "Devcon". These are a tool for the practical nerfsmith or structural plastics fabricator that I absolutely cannot overstate the utility of.

A general overview

Adhesives have a bad name in nerf. There have been far too many failures and flaky results over the years, but these are almost always caused by inept methods and simple use of the wrong tool for the job, not complete unsuitability of the entire class of adhesive assembly methods, which is extremely broad. Adhesive bonding and solvent welding, particularly of plastics, should never be counted out - and in some cases is indisputably superior, provided the correct methods and materials are involved.

Frequently "the job" in this hobby is:

• To create an effective single unit from two or more pieces of a bondable plastic*

• To bond a plastic to another material, such as a metal or a composite

* Bondable plastics include ABS, from which a great number of stock nerf gun parts are made; other styrene-based plastics such as PS, SAN, HIPS, etc. which are similar to ABS; PVC, which is frequently used as a cheap and mechanically high-performance material by hobbyists; polycarbonate; acrylic, and many others.

For these uses, methacrylates like "Devcon" should always be a consideration! They excel where others often fail.



A note on Devcon

Let's get this straight: Devcon is a company (ITW Devcon, Inc.) and a brand of adhesives and similar products. You can go here and check them out.

The company has a full line of hardware store 2-part adhesives branded "Devcon" that you may have seen, including many epoxies. But the term "Devcon" in the nerf hobby is almost ALWAYS referring to Devcon Plastic Welder and its relatives.

Shown here is its current retail packaging on the left and the older on the right, which you may have seen at some point. This product is available both at hardware stores and from more specialist suppliers (in which case the familiar old Devcon logo will still be used).

When Devcon... isn't Devcon

There are a number of competing and other brand products of this type in the hardware store market, including Permatex and other rebadges of the Devcon product (recognizable by the Devcon tube), but the most notable is Loctite's Plastic Bonder:

Note the presence of the term "epoxy" - long story short, it's wrong and is there for product recognition. We will get to that later. However, of special note is that the Loctite packaging for their Devcon PW knockoff is labeled "PLASTIC BONDER" and "Fuses Plastics". Beware a similar product without these markings, because that stuff is not methacrylate.

You may also buy MMA adhesives from industrial/specialty sources, in which case, do your homework on the manufacturer's website and use something appropriate. Devcon has a "Plastic Welder II" that may come in handy for applications involving nylon and other difficult plastics.


Performance characteristics, and comparison to epoxy adhesives

The main reason to use MMA adhesives rather than alternatives in nerf is inherent to the chemical constituents. Methyl methacrylate itself is a solvent for most bondable plastics. Thus, the terminology "weld" or "fuse" is not incorrect; significant fusion occurs when a MMA adhesive contacts a material like ABS or PVC. If you spill a little Devcon and try to scrape it off, the surface of the plastic will be softened, just like you may have noticed while using solvent cement to weld PVC piping systems together. The result of a Devcon joint is a weld, with a seamless transition from i.e. ABS into the cured acrylic resin of the adhesive.

This is in contrast to epoxies, which have no solvent property, create absolutely no fusion and function only as a glue producing a much weaker mechanical bond.

MMA's solvent properties also extend to surface contaminants. Combined with the lack of dependence on surface roughness to achieve "keying" (often emphasized by epoxy users as of prime importance) due to the solvent-welding action, MMA adhesives are very carefree to work with. I have made bonds between pieces of completely unprepared, 15 year old, oxidized PVC that had been sitting outside in the sun, and was unable to break them without failure of the material itself. That said, sanding is always cheap insurance and is necessary on metals and other materials that cannot be dissolved.

Epoxy, however, is very sensitive to prep and cleanliness. Oil, silicone residue from injection molding release agent, oxidation or even just a glossy ABS surface can make epoxy fall right off.


The second main advantage to the MMA "plastic welders" is the plastic-optimized mechanical properties. The cured resin, unlike most consumer epoxies, is a very tough and impact-resistant material and has similar characteristics to i.e. ABS and PVC; thus there is not a major modulus mismatch to create stresses in the bond, as occurs when you have rigid JB Weld (epoxy) or 5-minute epoxy in contact with ABS.


Wait. Plastic epoxy?

Confusion of 2-part methacrylates with epoxy is very common. Consumers will call any 2-part glue epoxy. Many nerfers have unwittingly called a methacrylate adhesive epoxy at some point, including noob me. Henkel/Loctite isn't helping. In fact, "epoxy" is used as a "product category" for 2-part adhesives by Loctite.

This is unfortunate, because it creates much confusion about the available adhesives and their performance.

So be aware of the difference. Epoxy and methacrylate resins are not chemically related in the slightest. Read the warning on the package - if it includes Contains methyl methacrylate and methacrylic acid or the like, this is the stuff you want. This is a surefire way to make sure you get the right stuff no matter what brand you use. Conversely, epoxies are always labeled with epoxy resin. That "non-Bonder" Loctite stuff, sure enough, contains epoxy resin, and not methyl methacrylate. Be a savvy buyer.


But there ARE gremlins!

What, you thought it really was a wonder material? Was I sounding like Billy Mays? Too good to be true?

Actually, there are only a few "gotchas" about MMA adhesives.

One is shelf life and environmental sensitivity. Epoxies store very well. You can use decades old epoxy. This is NOT true of methacrylates. Unlike epoxies, the resin is not a simple system of 2 monomers that react automatically on mixing, it involves a small amount of "activator" which triggers polymerization. This activator is sensitive to heat and ages rapidly, and as it degrades, the resin may cure slowly, not at all, or may not achieve its full properties.

As a result:

• Devcon has a shelf life. Only buy as much Devcon as you think you may use soon. For most of you including me, that is ONE tube. Do NOT stock up. Do NOT buy from a store that never moves any product. Go to the busiest supplier you can find.
• "Store in a cool dry place" is not a generic suggestion. Store Devcon AWAY from heat sources. A hot car is NOT the place for Devcon; I have had multiple tubes go bad from my toolbox being left in a car! Sometimes I put Devcon in the fridge.
• ALWAYS test an unknown (stored, newly bought, etc.) tube of Devcon by mixing up a small batch BEFORE using it on a critical application! If it doesn't cure HARD within the manufacturer's specified cure time, be suspicious! If it doesn't cure hard within a few hours, it's a total loss, go get a new tube!

The second big "gotcha" is that some metals, such as copper, inhibit MMA curing. Do not use Devcon to glue brass tubing, as the bond will never achieve strength. This is an application where epoxy is a better choice. Steel and aluminum, however, are perfectly fine.

Also, MMA adhesives have a distinctive sharp acrylic odor (the smell of MMA vapor). I am used to it; the smell of Devcon is the smell of work getting done and impending zombie annihilation! However, ventilation is probably desired. You can really stink a place up with the stuff.


Miscellaneous usage considerations

"Plastic welder" is a 2-part adhesive - most nerfers are familiar with epoxy usage. Dispense the correct quantities as specified (usually equal volumes in consumer products) and mix very thoroughly, then apply to part to be bonded, assemble and let cure.

Some "dual syringe" tubes fail to dispense evenly. I usually cut the 2 plunger rods apart and operate each independently. MMA is not very sensitive to mix ratio variations; and these tubes usually don't measure any more accurately than "eyeballing" the quantities (in fact most end up way off), so you can save on wasted product from a malfunctioning tube by separating the plungers and estimating the correct ratio.

Most "plastic welders" have excellent gap fill characteristics.

As an alternative to solvent welding and thermal welding

Consider "plastic welder" if you were thinking of using either aforementioned processes.

Solvent welds are typically weaker than the base material because of voids/poor structure. True solvent welding involves a solvent that evaporates or diffuses away, so the joint shrinks. Pure solvents and almost-pure solvents like MEK, Weld-On 3, etc. have absolutely zero gap fill and require perfect fit and interference to bond parts. Even filled solvent cements (like PVC and ABS pipe cements) that contain added plastic resin will still shrink, create voids and fill gaps poorly as the solvent is present in the initial adhesive but not the final bond.

By contrast, MMA still achieves fusion but is 100% solids. It cures by polymerizing, not by evaporation of solvent, and doesn't change volume in the process.

Thermal welding without specialized equipment similarly creates a weak joint. Save your soldering iron tips for soldering and quit breathing ABS fumes. MMA adhesive will make a stronger result and is easier to use and add material to a joint with.

As an alternative to mechanical fasteners

"Mechanical fastening" is a buzzword, particularly in the Proper NIC, and is frequently listed as a feature: "No adhesives - 100% mechanically fastened" (specifically referring to cases where mechanical fasteners such as screws or bolts are used to replace an adhesive or weld rather than where removability is required). This is due to that previously discussed mistrust for adhesives and history of failures. Since epoxies are often regarded as the go-to structural adhesive in nerf and alternatives are infrequently encountered for applications like installing grips and integrations and doing structural mods and repairs, it is easy to see where the idea originates.

However, the idea that mechanical is superior is flawed. Often, a mechanical joining of two parts creates stress concentrations and the seamless bonded or welded part would be stronger, cheaper and cleaner - of course, given that a weak or incorrect adhesive or bad workmanship is not there to throw a wrench into the matter.

MMA "plastic welder" on ABS, PVC et al. is certainly an example of a proper adhesive selection, and one that can actually perform better than any mechanical fastening in some cases since a uniform area (rather than individual fasteners) applies forces to the material.

Example usage of MMA adhesives in nerf

Um, Read this blog? Everything I do... 90% chance the stuff is there! Some notable and some mundane examples below:

 "Lockheed Bot": Devcon was used to bond an aluminum bracket and a steel hinge half to an ABS nerf gun receiver after continual problems with failure of screws and bolts. Introduced me to the use of this material.

Stryfe Cyclone: Devcon was used to fabricate motor mounts and the custom stock.

 

Numerous underslung integrations: Devcon was used to bond ABS clamshells to produce barrel shroud/handguard sets with integrally mounted Swarmfires, Rapidstrikes and Roughcuts. All of these have minimal bond areas and are subjected to considerable mechanical abuse from gameplay.

Oblivion Rifle: A Stryfe was structurally modified and fitted with scratchbuilt shrouds and other parts to create a prop replica. The materials were mainly PVC and ABS. All structural bonding, with very few exceptions, was with Devcon and Loctite Plastic Bonder.

 

RP Alpha Trooper: Devcon was used to bond a steel reinforcement to an ABS plunger tube. This application is subject to heavy shock and vibration that could crack or delaminate epoxy from the ABS. The part has been in service since mid 2011 without failure. Additionally, Devcon was used to repair and bond a reinforcing gusset to a cracked sear lug, which was initially stock, on this same PT at a later date.


Grips and trigger packs: Devcon has been used in many installations of integral pistol grips, trigger units and the like on clamshell host parts. This is a very failure prone application in many cases, since the bond area is small and the protruding grip offers much mechanical advantage when a gun is hit, fallen on, etc. This includes use on a circa 20lb (equipped and loaded) Vulcan.

Stampede BCG: Devcon was used to repair a busted-up bolt group and fabricate the destroyed endplate.

Countless others have been left out, but rest assured, if I did it, Devcon is holding it together. What is surprising even to myself is that despite all the abuse HvZ gear gets from me and others who use my work, not one of my Devcon joints has ever failed. Generally, if a structural failure is to occur, adjacent parent material will break long before anything happens to the Devcon bond line.

So if you don't use this stuff already, give it a shot. I guarantee it will change the way you build.

Rapid Upgrades and Rambles.

This last few days saw a lot of Rapidstrike tweaking.

Following the testing of the OMW Swarmfire spring, it was clear my RapidSwarm (my current stock class and HvZ workhorse) had to have it. Also, a fellow member of the squad proposed a hybrid type of grip design for a proper Swarmfire trigger/foregrip on these and requested that he finally get the recommended Swarmfire upgrade. Finally, I finally got the Rapid² back. Finally. It had been loaned, along with a battery pack, to a player last game - so this was my first opportunity to install its new custom battery pack in the correct location.

Up first was the RapidSwarm.

Here is where design for service comes in handy. The entire front assembly, including the barrel shroud, inner barrel, flywheel cage, front sight and Swarmfire receiver are a lift-out module. No annoying workshop worthy procedure here.

  

Note that the mechanical modularity is inherent when you do the Swarmfire install properly. What isn't inherent is that this entire section of the wiring harness unplugs.

That is a wise decision for RS builders. It only takes a minimum of 3 pins (for front-wired or Swarmfire equipped guns) or 2 (rear-wired and non-underslung equipped) of power connectors of your choice to do the basic common builds. The magwell area has adequate room to place these connectors and secure the wire.

CT-0268 also had me install the VFG/trigger unit (mentioned below) on the original RapidSwarm's twin, but he elected to omit the connectors at build time to save pocket change worth of parts, resulting in a tedious Swarmfire upgrade and grip install.

And here's a nice visible example of flywheel buildup after a recent test of elite darts. A lot of nerfers know this rubbery stuff that accumulates on flywheels from high-speed, high-temperature contact with dart tips and foam.

But what continues to baffle me is that the default assumption is that this phenomenon is somehow a problem.

Flywheel buildup is a normal and functional part of high-end flywheel gun operation. Dart damage will drop off and velocities will increase significantly after a new clean flywheel set has developed its buildup layer.

Note that the buildup self-aligns to the assembly of the gun: cage to magwell alignment, flywheel axial position on the motor shafts... It's a lot more accurate than you are (without machine tools and overkill measurement methods). In fact, it almost forms a concave surface in this example, and at the very least, will correct for any taper of stock flywheels that is a usual suspect for accuracy problems.

So don't worry about it. Don't clean your flywheels. Don't apply stuff to them either. One, the gap is probably correct from the factory. Two, mark my words about Delrin objects rotating at high speed being a bad place for anything adhesive. It will shred. When? Who knows. Probably when you are about to get tagged.


The best way to get flywheels gripping better and running truer is to go to the range and burn ammo.

So, the spring was dumped into the Swarmfire, which was cleaned and lubed as always (anyone who tells you that putting "nerf" before "gun" somehow magically exempts you from maintenance requirements has never cleaned an HvZ gun and seen all the shit they collect!) and performed as expected. But we have had enough images of Swarmfire guts, you know what working on Swarmfires looks like.

I also modified a Swarmy cylinder retainer with a steel grip loop to allow quick cylinder dropping in the field (the idea is to tie the retainer to the gun with a piece of paracord or something so that the retainer can't get lost). That will not be implemented in combat. Not yet. Why? It's real dumb... I can't think of a sound way to carry the damn cylinders. They are an awkward device, and they have darts protruding that you don't want to dislodge or mangle. This calls for a specific piece of tac gear, a Swarmfire cylinder bandolier or a MOLLE Swarmfire cylinder pouch/clip or something.

So here's the VFG/trigger pack that CT-0268 devised, based on a Retaliator-type Nerf VFG (a common and often unwanted accessory) minus the junk railgrabber it comes with. The combination of a vertical grip with a trigger is odd. Reminiscent of an RPG launcher, perhaps. I would not have come up with that, and I recommended a real pistol grip, but it works.

His got a "stock" dual-contact switch salvaged from something Nerf, along with a Stampede magwell interlock button, which resembles a grip switch button when installed.

I was not to be one-upped, though. Sure, I did that work, but I wanted to go one step farther and upgrade to a microswitch and a proper ergonomic trigger.

I fabricated the trigger from PVC sheet, installed a steel pin for the trigger pivot and used the usual full size microswitch, with no lever actuator. The result is extremely crisp and has a very short pull. Just the ticket for my snappy new 90-100fps Swarmy and its higher amp draw...

 Here you can see the trigger/switch arrangement and how short the stroke is on that.

 And the trigger removed.

 And the trigger itself.

Ah yes. You should ALWAYS have a trigger guard.

Negligent discharges of these Swarmfires have been a major problem with the old side trigger system. Initially, CT-0268's gun did not have a guard on the new grip assembly, but a few days later it was clear I was not crazy to suggest a guard. I fabricated a guard on the spot with some PVC sheet heated over a stove burner and bent. Slammed it on with Devcon. Problem solved.

My install got the exact same guard from the start.

Now, in my case, there was a certain problem with the change to the foregrip trigger: I am a habitual mag gripper when I handle rifles, ever since the Stampede era, and find I can get the fastest sidewise engagement of a sudden target (such as a dodging zombie) by mag gripping my rifles. Keeps the mass (of the support hand and arm) pulled in tighter, less inertia to swing around. Thus I tend to shun VFGs and foregrips in general. My old side trigger rig could not go, it had to remain for snap reaction use, since I will not be using that VFG continuously.

So, it got a separate safety, solving the problem of Swarmy NDs and not being able to chuck the gun into a car trunk without it going off.

So here it is.

Up next: That stick battery install into the Rapid².

This stock had already been prepped for a stick battery as covered a while back and I had also made the pack for it, a slightly shorter while back. It is a 2S, using the Sanyo UR18650SAX cell as all of my budget packs have.

(A note on the state of the big Li-ion changeover: It is a huge success, the packs are all troopers. I cannot understate how awesome being able to check state-of-charge with a voltmeter is. I also cannot understate how awesome the low self-discharge is. In the time since last game and following Worldfire events and other nonsense, many nickel packs of mine self-discharged, built up voltage depression and went out of balance, and had to be slow charged and cycled to get back in the game. Meanwhile, the 2S Li-ion from the loaned Rapid² didn't even need a charge!)

All it took was a quick wrap with some sock material to provide some impact protection and stop rattling, and you would never know it's there. Light and unobtrusive.

"Where the hell is the battery for that thing?" 

Take that, Trustfire Brigade! Can't get a junk AA holder into here now, can we...

Unfortunately, with this choice of battery location and the particular way I implemented the stock, the RS has to split to access it, and that includes charging.

A spare female Deans and a balance tap extension tucked inside a tool-free access cover on the receiver would solve that VERY nicely. You don't want to charge lipos while they are installed in something, but these packs aren't lipos, and are about as safe as 3.7V chemistry Li-ion charging gets.

When I get around to it, I guess.

With the current motors in this unit and occasional use there is no big problem with battery life.

So on another note... Anyone remember this beast?

The Cyclone DMR.

That wss a time in my HvZ career where I had run several games with my trusty Swarmpede, and proven the rifle/Swarmfire deal was my stunning tool of choice... but I wanted to give a more civilized weapon a try. This was it: long-barreled, iron-sighted, semi-automatic, equipped with monstrous high-end motors and a flywheel configuration that works to defy the conventional logic of barrel length and flywheel accuracy, and it remains the sweetest handling nerf gun I am aware of.

Recently I brought it out to advertising and got some clean shots on zombies that my Rapidstrikes could never hope to match.

There is something to be said for that whole concept.

Don't get me wrong, I'm not going to full-scale-game this gun any time soon. But it still is just as good at what it does as I designed it to be, even today.

At least after I clean the sticky trigger.

Damn gremlins.