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The Singledstrike

How to single your DoubleStrike

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#1 Majestic

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Posted 11 June 2015 - 02:13 AM

How to single a Nerf Zombie Strike Doublestrike and create the “Singledstrike”


I love a blaster that can be primed and fired with one hand only, so when I saw this blaster on sale at Target for $8 I could not resist bringing it home and making it awesome. The following is my attempt at making a war-worthy, single-shot, front-loading, last-resort style blaster that can compete with a mildly modified Firestrike.

Let’s turn this……..
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Into this…………
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This is what you will need:
Nerf Zombie Strike Doublestrike
http://www.target.co..._1_51&term=nerf
Small Phillips head screwdriver
Hammer
Nail
Pliers
Dual setting hot glue gun
Tube cutter
Saw
Blowtorch
Scissors
De-burrer
Coarse (black) nail file
Sand paper
Tape
Cup
˝ in wooden dowel rod
Dremel tool
Calipers
Ruler
˝ in PVC coupler
17/32 brass tube
Wooden block
Soap
5 minute epoxy
˝ in brass tube
˝ in PETG (optional)
And this is what you do with it….

Dis-assembly


1) Remove seven (7) screws and put them in a cup to keep them safe. They are all silver and all the same size so remembering their locations not important.

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2) Clamshell the blaster, and put the tac-rail clip and its spring in cup with the screws.

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3) Remove the barrel assembly, hammer/plunger assembly, main spring and its perch. Remove the trigger group and put it in the cup.

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4) Remove the O-ring from the plunger. Using a nail and hammer, gently punch out the pin holding the plunger to the hammer. Notice the pin is knurled on one end, hammer on the opposite end. If it is not immediately apparent which side is knurled, notice that one side is slightly more recessed than the other. The recessed side is the one to pound on.

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5) The inside of this blaster is extremely well lubricated. With hot soapy water wash it all off. Put the O-ring, and hammer in the cup. Now warm your hot glue gun.

Delete Air Restrictor (AR) and dead space


1) Fill the cavity in the plunger with hot glue. To keep it level, I rest mine in a ˝ in PVC coupler. My hot glue gun has two settings; I use the low setting to fill the holes first so that the plastic does not warp from the heat. Next I crank it up to fill the last 1/4 in and hit it quickly and carefully with a blowtorch to get everything nice and smooth. Set the plunger aside and let it cool. Then mount it back on the hammer assembly. Large pliers work nicely to press the pin back in. Set the assembly aside.

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2) Remove two (2) screws from the barrel and put them in the cup. Note that they are longer than the screws in the shell.

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Stand the barrels upright and push down hard on the dart peg with a piece of ˝ in wooden dowel rod to remove the smart AR unit. Wash the grease out of the plunger tube (PT) with hot soapy water.

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3) Cut off the dart pegs and attack the ARs with a dremel tool. There is a lip inside that must be shaved smooth to delete the AR and widened to fully fit a dart. When you are finished, wash your unit.

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4) Fill the lower AR and the inner hole in the upper AR with hot glue and let it cool.

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5) Cut a piece of cardstock that is 1.5in x 3in, roll it up and stuff it into the upper AR.

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Cut a second piece of cardstock to 2in x 4.5in and tape it around the AR unit.

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Fill the empty areas in the back of the AR unit with hot glue avoiding the air channel for the upper barrel. Sit it aside and let it cool. Take the paper off and fill any gaps with hot glue.

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Singling


It may not be obvious why it is a good idea to take a blaster that fires two shots and make it only shoot one, but after extensive modding and testing I have found that the lower barrel never shoots consistently or nearly as hard as the upper one. In my opinion it is cooler to have a blaster that shoots one shot really well than one that shoots the first dart acceptably and by comparison farts out the second.

1) Carefully cut the upper barrel off about an inch down from the tip. I left the very tip on to cover the brass we are about to put in and because I thought it looked fancy. Now sand the inside of the barrel with heavy grit sand paper wrapped around the dowel rod until a 17/32 brass stub will fit inside. The I.D. of the barrel necks down about 8mm from the plunger tube, don’t sand this part. Hammer the brass until it hits this point. Do not hammer directly on the brass or you will deform it badly. Use a block of wood instead. With a tube cutter or saw, cut the exposed brass so that it covers the darts you plan to use completely but you can still push them in all the way with your finger. Then deburr it with a deburrer and sand paper. I leave the lower barrel intact to store a second dart. I covered the exposed brass with a piece of ˝ in PETG and used epoxy to fix it in place. This was a totally aesthetic choice and is completely optional, but I think it looks neat.

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2) After you are done cutting and sanding, thoroughly wash the plunger tube assembly and the AR unit in hot soapy water. Rinse and let dry.

3) There is a small air channel in between the barrels on the face of the plunger tube that needs to be plugged for a complete air seal. Spread a layer of epoxy on the face of the AR unit and press it into the plunger tube. When it reaches the limit of what you can do with your hand put the screws back into the plunger tube and evenly screw them into place to fully seat the AR unit inside. This is the last step in singling this blaster and you only get one shot at it. Take your time and make sure everything lines up nicely and the barrel does not get clogged with epoxy.

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Spring Spacer


Now that a number of supporting modifications have been done to focus the air flow and make the plunger system more efficient, let’s make some POWER! In stock form, if the hammer is pulled back beyond the point where the trigger engages, the Doublestrike has a nasty habit of pushing the dart out of the barrel slightly. Adding a properly sized spring spacer helps combat this by removing a lot of the excess travel of the hammer during priming.

1) Get out your calipers, tube cutter, de-burrer, file, ˝ in brass, and ˝ in dowel rod. Cut, de-burr, and file smooth a brass spacer 9.5mm long. I nest the rod inside the brass while using the tube cutter so that the end of the pipe barely deforms. A saw will also do the job.

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2) Tack the spacer to the spring perch with hot glue. It will need to be biased toward the trigger so that it clears the hammer stop. Put the guts back in the blaster and test it’s functioning. When it is working well, fill the brass with hot glue and set it aside to cool.

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Note: 9.5mm does not give the spring full compression. The trigger catch will not engage with a spacer large enough to compress the spring fully. Under the trigger guard there is a serial number etched into the shell, I have noticed there are slight differences in the design between models. 9.5mm might not be the optimal size for all models, but it has worked well on the ones that I have modded.

Reassembly


1) Lubricate the plunger, and O-ring, with silicone grease. Don’t forget to lube under the O-ring as well as the inside of the plunger tube. Push the plunger/hammer assembly into the plunger tube and seat it in the blaster shell.

2) Replace the trigger group. Note that the trigger spring must rest all the way against the shell with the end that does not connect to the trigger pointing toward the barrel.

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3) Impale the main spring on the hammer assembly and squeeze the spring perch in to place. This can be tricky as the internals will try to liberate themselves constantly during the process.

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4) Replace the tac-rail clip along with its spring and place the two sides of the shell together. Screw the 7 screws back into place and you are ready to go own newbs.

I decided to paint this blaster with a nationalistic paint scheme in time for Independence Day. The base is two coats of grey Duplicolor vinyl dye, followed by two coats of red Duplicolor vinyl dye, which I let cure over night and then wet sanded smooth with 800 grit sandpaper. The accents are all Citidel, the colors I used were White Scar, Ceramite White, Macragge Blue, Temple Guard Blue, Evil Sunz Scarlet and Nihilakh Oxide. The dry brushing was done with Testors Metallic Silver. I sealed it with 2 coats of Rust-Oleum Gloss Automotive Enamel which creates a supper hard finish, and wet sanded again with 800 grit sand paper. Finally, I applied two coats of Rust-Oleum Matte Finish to remove the sheen from the clear coat and give it a more comfortable feel in the hand.

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I did range tests with three different darts, standard blue elite’s, green Zombie Strike elite’s and Mostly Harmless Arms (MHA) pink foam silicone tipped darts. Four darts of each type, both angled shots and flat shots. Please note that these are approximate as I do not have a legitimate firing range. I just fire them in the alley behind my house and pace them off. Also, the shots are listed in the order that I picked them up off the ground, not the order in which they were fired.

Blue Elite’s:
PTG shots Angled shots
1. 69 ft 1. 96ft
2. 72ft. 2. 105ft
3. 75ft 3. 108ft
4. 78ft 4. 117ft

Green Zombie Strike darts
PTG shots Angled shots
1. 63ft 1. 108ft
2. 63ft 2. 120ft
3. 75ft 3. 126ft
4. 96ft 4. 126ft

MHA darts
PTG shots Angled shots
1. 69ft 1. 87ft
2. 69ft 2. 90ft
3. 72ft 3. 99ft
4. 75ft 4. 102ft

It is worth mentioning that the barrel is not optimized for MHA foam and were I to make one that is Stephan compatible I’m sure that the benefits would be measurable.

Stock performance was about 45ft flat from the top barrel and 30ft from the lower one. As you can see these modifications add up to some major improvements. But you don't have to take my word for it. I'll see you next time.
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#2 ompa

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Posted 11 June 2015 - 02:36 AM

Simple, easy to do with the most basic of tools, and effective. The bottom barrel firing tends to be due to a slight issue with how the hammer functions (as far as I'm aware of, it goes a bit too far back and the extra air pushes the dart off the restrictor a bit, screwing with ranges), but regardless it's still a nice modification with a clean paintjob to boot. Thanks for the submission!

I also enjoy the extinct animal book followed by shots of the blaster on leopard print; I laughed.
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#3 Majestic

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Posted 11 June 2015 - 02:03 PM

I made mention of that little phenomena

In stock form, if the hammer is pulled back beyond the point where the trigger engages, the Doublestrike has a nasty habit of pushing the dart out of the barrel slightly. Adding a properly sized spring spacer helps combat this by removing a lot of the excess travel of the hammer during priming.


I did the spring mod then tested it on an intact AR. The lower barrel was still crappy compared to the upper one and the ranges were nowhere near as spectacular as in the final version. I think the real issue it that while the system is reasonably air tight as a whole(as can be seen demonstrated on many a youtube channel), there is pneumatic communication between the barrels. Epoxying the AR in place solves this. What I did not do is epoxy an intact AR into place and see if that fixes the air transfer between the barrels on its own. If I had done that and it did not fix the leaks it would have made removing the AR's very difficult leaving me with a ruined blaster. I was aiming for Firestrike-like single shot performance any way. I would be interested in the results if anyone else would care to try it.
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