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Rtp, Pump Action Homemade.


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#1 Split

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Posted 04 June 2010 - 10:05 PM

The goal of this homemade was just to make a working pump action homemade where you didn't have to move your hands to prime the gun. I went though many many designs for that goal, but most relied on a separate handle that would have to be carefully constructed to handle the torque from pulling back the plunger rod. I eventually settled on this relatively minimalist design. There are only 7 parts to cut for the base model, not including whatever handle you decide to use.

::Disclaimer, I'm really tired right now, so some parts of this may be a bit unclear. If anything is confusing, just let me know and I'll do my best to remedy the situation.::

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::See bottom for firing video::


First, you need to download and print your Templates
Make sure you have everything from the Parts List.

1) Cut them out, paste them onto your plastic. The two plain circles with yellow coded centers are from 1/8" thick polycarb.
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2) Drill out the holes and cut out the appropriate parts, as per the legend and templates. Except for the 1/8" thick parts, tap all holes coded yellow with a 10-32 tap. When you cut your circles, the tapped one and the circle center/untapped one need to be able to move through the plunger tube easily. The last circle should fit firmly in, but not too tightly.
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Ignore the odd holes I drilled in some of the templates. I was testing out different sizes of plunger rods.


3) You'll need a scroll saw for this part. Feed the blade through the holes marked as squares and cut out along the line.
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4) Before removing the paper from all of your parts, you'll need to mark the direction your parts need to face. With the template side facing up, turn all of the circles so that the dot is at the top. Now, mark all of the sides with an L (or other asymmetrical symbol). You can now remove the paper if you'd like.
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5) Line up the tapped circle and the square center circle in the way they need to assemble and vice them. To the sides, drill and tap straight through them with a 5/32" bit and 6-32 tap.
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6) Start feeding 1" 6-32 screws through the tapped circle until 1/2" is sticking out. Push the other circle onto the end and finish threading the screws through. Once you're done, it should look like this and measure 1" long total.
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7) Take four threaded rods and screw four locknuts on until they are 5/8" from the end (5/8" gap, not including the body of the nut itself). Now thread rods through your circle-center, untapped hole, then through the square center and then into the threaded circle. Thread one up until the end is flush with the circle, and thread the rest so that a little more than 1/4" is sticking out.
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8) Push your catch onto the end of the rods, followed by the washers. Line up the rod sticking out the most with its respective hole on the back plate. Rotate the back plate until it's tight against the other three rods. Rotate each of the other rods so that they thread into their respective holes. Make sure your catch moves smoothly and your loose plate slide along the rods nicely.
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9) Now you'll make your plunger tube. It needs to be 10 5/16" long from 1.5" OD polycarbonate tube if you're using a 1 1/4" long bushing. If your bushing is shorter, make the tube shorter by the same amount, and vice versa. Goop/e-tape/o-ring or whatever you want to do, but seal the bushing to the end of the tube, and secure it in nicely. I used goop, e-tape and a 2" bolt through the entire thing, a la +bow.
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10) This is a good time to mount your gun body onto a handle or larger shell. For this, I just used a maverick handle and corresponding trigger. You'll also need to tighten those locknuts down onto the catch as much as you can, while still letting the catch move freely.
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11) From here, you need to attach the tube to the body. Move the sliding piece all the way to the catch and push the plunger tube all the way down onto it. Drill through the end of the plunger tube and into the sliding part with a 5/32" bit and tap the hole. Screw in a 1/4" length screw. Mark the plunger tube with the L. Don't worry about it breaking here, this part isn't load bearing. If you did it right, there should be a nice 5" gap.
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12) Slide your tube assembly down the rods a little bit so that the spacer is in a comfortable angle for sliding. Drill, tap and insert three more holes and screws through the tube and into the spacer. It should now move very smoothly.
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Caution: I'm pretty sure this video is nsfw. Pull out my dick have sex with your mom and everything.


13) Here you'll just want to make your plunger rod. The length for this should be 8 5/8" plus the distance from the back of the plunger tube to the back of the catch when the gun is collapsed. This should be about 1/2", making your length about 9 1/8". Cut your notch starting 3/8" from the end, and drill and tap the opposite end. Screw your plunger head between two 1/8" thick circles into there.
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14) Cut your spring to any length between 7 1/8 and about 8" (the longer it is, the harder it is to prime, but the more powerful). Lube up your plunger tube, insert your plunger rod, notch up, then your spring. Push the body of the gun onto the back, and screw the spacer into the back of the plunger tube. It should be done now, bearing the tons of fine tuning you'll need to do.
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If you didn't catch it, at the end of the video I mention how you can use this as a hamp-type mechanism for mercy kills. This system is pretty powerful, and I hope to see it adapted to many uses. It's certainly not the typical pump action method, but it sure works nice.

That should be everything. Enjoy.

Edited by Split, 06 June 2010 - 08:49 AM.

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#2 jwasko

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Posted 04 June 2010 - 10:25 PM

I just used up all my polycarb and two Mavs on a homemade. Why couldn't you have posted this two days ago?


But, seriously, I love how similar it is to a Trigger Fire (aka Badger's "Boomstick") without the need for gears.

The "HAMP action" is a nice ROF boost (when combined with a hopper or whatever, of course)...the only feature that I would (personally) attempt to add is something that prevents a trigger pull until the grip is pulled all the way back.


Also: any chance of seeing the internals of the Mav handle?

Edited by jwasko, 04 June 2010 - 10:30 PM.

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#3 b1g13en

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Posted 04 June 2010 - 10:49 PM

This is a very cool homemade but doesn't the 3b function just like that?
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#4 Fome

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Posted 05 June 2010 - 02:21 AM

Damn, that's cool.
That workshop of yours is definitely not wasted man.

This is a very cool homemade but doesn't the 3b function just like that?


It appears from the video that it's more like a PAS or lanard shotgun. In the 3b, you're pulling with your back hand or pushing away with your front, opposite of what seems to be going on here.

Looks hard to prime though, kinda detracts from the ROF, no? :P

#5 ficksterkid

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Posted 05 June 2010 - 08:22 AM

Wow, another exceptional and unique homemade.
Nice job!
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#6 BritNerfMogul

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Posted 05 June 2010 - 09:05 AM

Ingenius.

But I do have one question. Does it feel weird using this firing style?
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#7 Split

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Posted 05 June 2010 - 09:43 AM

I just used up all my polycarb and two Mavs on a homemade. Why couldn't you have posted this two days ago?

I wouldn't want you to have a gun like this, obviously. What if you showed up to one of my wars? That'd just be too much. :D

The "HAMP action" is a nice ROF boost (when combined with a hopper or whatever, of course)...the only feature that I would (personally) attempt to add is something that prevents a trigger pull until the grip is pulled all the way back.

I considered it; it would be tricky, and undoubtedly add some reliability issues, but it is possible. Simply because of the way the circles fit together though, the plunger tube doesn't slide freely enough when it's closed (a slight twist in the square pattern for the rods translates into a noticeable difference over 7") so it doesn't slide back before it's primed unless you make it. Otherwise, I haven't had any relevant issues here.

Also: any chance of seeing the internals of the Mav handle?

Yeah, I'll get a picture up later today probably.

This is a very cool homemade but doesn't the 3b function just like that?

No; the scorpion bow and 3b compress the spring as you pull the sections apart. This compresses the spring as you push them together. It's a different feel completely and certainly doesn't work like them.

Looks hard to prime though, kinda detracts from the ROF, no? :P

Yeah, I mentioned in the video that I made the spring too long and it's a pain in the ass to prime right now. The original was a 1" shorter spring and it was shooting off a whole 12 shot hopper in about 8-9 seconds.

But I do have one question. Does it feel weird using this firing style?

It certainly uses an odd set of muscles. I feel my lower left tricep tensing up. In general though, it's very ergonomic like this. I favored it like this over the original plan actually:
Posted Image
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#8 taerKitty

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Posted 05 June 2010 - 10:16 AM

Sweet job. The action, especially with the vertical foregrip, appears to be very natural - force your hands together, then slide them apart without additional force. (And, repeat for HAMP-like firing.)

Very clean cuts, very nice look.

Would it be overkill to suggest this sport a RIS clamp so it can be underslung-mounted? Seeing the trigger on the front Mav handle brings to mind the image of it under a larger primary, dispensing with the original main handle.
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#9 Wes7143

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Posted 05 June 2010 - 12:47 PM

So, this is basically a homemade BBB? Or is there a notable difference in how it functions?

Edit: Disregard that question. I forgot that the BBB compresses the spring on the push instead of the pull. However, it looks like the placement of the catch in regards to how the plunger assembly interacts with it is similar.

Edited by Wes7143, 05 June 2010 - 12:50 PM.

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#10 Broderick

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Posted 05 June 2010 - 10:27 PM

I have to say, this is pretty bad ass. These last few months you've really been pumping out new designs.
Do you get the feeling of it being a little... skimpy? I'm not really sure how to put it; like there's not enough blaster there, for how long it is, you know?
EDIT: TaerKitty made me aware of how that may have come across... I wasn't meaning that as if you hadn't put enough work to it or anything, I just meant if you felt there wasn't quite enough material there. But taerKitty brings up a good point in his post.

Edited by Broderick, 05 June 2010 - 11:12 PM.

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#11 taerKitty

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Posted 05 June 2010 - 10:46 PM

I have to say, this is pretty bad ass. These last few months you've really been pumping out new designs.
Do you get the feeling of it being a little... skimpy? I'm not really sure how to put it; like there's not enough blaster there, for how long it is, you know?

Speaking only for myself, skimpy is good. Less parts = less weight, less cost, less complexity. Now skimping is different - I'm sure Split didn't skimp on the mounting hardware, and the quality of the parts speak for themselves.
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#12 Split

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Posted 06 June 2010 - 07:58 AM

I have to say, this is pretty bad ass. These last few months you've really been pumping out new designs.
Do you get the feeling of it being a little... skimpy? I'm not really sure how to put it; like there's not enough blaster there, for how long it is, you know?

Speaking only for myself, skimpy is good. Less parts = less weight, less cost, less complexity. Now skimping is different - I'm sure Split didn't skimp on the mounting hardware, and the quality of the parts speak for themselves.

Yeah, that's pretty much spot on. be sure to carefully thread the holes (I stripped one on the original which led to its downfall) and find the right locknuts.

This is more of a barebones than anything. Because it's only ~1.75" wide at the biggest part, it can fit into most shells and things. There are lots of ways to beef up the body. I liked the idea of having a plate in front of the catch instead of the lock nuts to which you can attach a 1 7/8" ID tube, providing more stability (not that it's all that flimsy) and making it easier for add-ons like a trigger lock.

Some things I've noticed about the design:
  • While it doesn't flop around all that much, it's still not sturdy enough to fire single handed. This should seem reasonable. If the plunger tube (which needs some amount of movement to slide easily anyway) can move by 2 degrees, magnify that over the 23" from the base of the tube to the tip of the barrel. It is nice to aim when you're holding it in both hands though.
  • If you keep it in the "closed" position at your hip, flinging it out does pull the plunger tube out if your action is smooth enough. Iz sweet.
  • (my favorite) To make the gun bigger or smaller (i.e., longer or shoter stroke) add/subtract 1" length to the plunger tube, threaded rod, and plunger rod dimensions for every inch you want to change it by and voila.
Templates and parts list should be up in a minute.
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#13 Broderick

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Posted 06 June 2010 - 02:08 PM

Some things I've noticed about the design:

  • While it doesn't flop around all that much, it's still not sturdy enough to fire single handed. This should seem reasonable. If the plunger tube (which needs some amount of movement to slide easily anyway) can move by 2 degrees, magnify that over the 23" from the base of the tube to the tip of the barrel. It is nice to aim when you're holding it in both hands though.
  • If you keep it in the "closed" position at your hip, flinging it out does pull the plunger tube out if your action is smooth enough. Iz sweet.
  • (my favorite) To make the gun bigger or smaller (i.e., longer or shoter stroke) add/subtract 1" length to the plunger tube, threaded rod, and plunger rod dimensions for every inch you want to change it by and voila.
Templates and parts list should be up in a minute.

I actually hadn't thought "integration" when I first looked at the gun, but with some integration brackets put on there, you could shorten like you said and put it under a Plusbow. Whenever I get around to buying one from somebody, I'll have to remember this.

Edited by Broderick, 06 June 2010 - 02:08 PM.

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#14 Split

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Posted 06 June 2010 - 02:25 PM

I actually hadn't thought "integration" when I first looked at the gun, but with some integration brackets put on there, you could shorten like you said and put it under a Plusbow. Whenever I get around to buying one from somebody, I'll have to remember this.

I'm trying to put new types of homemades out there, making them cheap and available. I'm trying to get people to move away from having everyone use the same gun. This is better than a plusbow in almost every way (cheaper, stronger, faster, easier to make, more comfortable handle, easier to modify), yet the first thing you want to do is slap it on a plusbow after weakening it... This is kind of an annoying trend I've noticed. The same thing happened with the LAB.
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#15 TantumBull

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Posted 06 June 2010 - 02:27 PM

This is awesome. I love the pump action without having any priming bars, bolt-sleds, or other pieces that take stress at bad angles in other pump action set-ups. Really excellent work.

Using this as an under-slung with maybe a spring return would be pretty sweet.
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#16 Galaxy613

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Posted 06 June 2010 - 09:26 PM

I'm trying to put new types of homemades out there, making them cheap and available. I'm trying to get people to move away from having everyone use the same gun.


And this is why I love your work. Don't stop. :(
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#17 Salmon

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Posted 06 June 2010 - 11:55 PM

In the words of the immortal Stephen Quire: "Dude. Freakin' WOW."

This thing is fantastic. It looks really comfy, too, even more so if you added a padded grip to the front. Only thing it's missing is a return spring, but I imagine that might hamper the HAMP mechanism. No pun intended.
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#18 taerKitty

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Posted 07 June 2010 - 02:12 PM

Using this as an under-slung with maybe a spring return would be pretty sweet.

I was suggesting it as the 'deterent' for an airgun, actually. This way, if someone tries potshotting the wielder while he's pumping, there'd be a lesson in store for him.

Hm... If it were to have a side mounted hopper like the SonReeceSonJensen's 4B dildo, there could be some serious insanity - mount the thing to the right side of a 4B, handle pointing out to the right. Attach the rear handle to the pump, the front to the 4B's body. Have the RTG hopper come in at a 45-degree angle from the upper rear-left.

Hold it with the 4B upright, left hand on the 4B's handle, upright, right hand on the RTP's handle, gansta-style. The RTG hopper is now 45 degrees upside-down, so it won't load while the right hand works the pump.

Now, rotate this monstrosity so the right hand is upright and the left is horizontal. The RTG hopper is facing the right way again, so a dart slides into home (and, when the trigger is pulled, out the business end.)

Requirement - the 4B's plunger draw must be the same as the RTP's.

Upside - your hands never leave the two handles, but you get the versatility of an airgun (assuming it has its own magazine system) and the RoF of a springer.

Downside - you're firing the 4B left-handed. Also, if the airgun's fully pumped, you can't do the HAMP-non-barrel-tap kill. Maybe shoot him in the leg? ("Ah, quit yer whinin', you gots another one.")

This sounds, like I said, insane. I don't have the scroll-saw, but I may make it, Snap-style and try it out.

Edited by taerKitty, 07 June 2010 - 02:17 PM.

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#19 Fome

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Posted 08 June 2010 - 12:51 AM

I just read your post 3 times taerkitty, and I still have no idea what the fuck the point of it was. Split said this thing hits harder than a +bow, why would you want to complicate everything by strapping it to the side of an inferior gun and developing a retarded way of firing it?

Whenever I make a rambling mess of words and incoherent thoughts that has barely anything to do with the original thread, I usually pause for a second with my cursor over the "Add Reply" button, and then promptly hit back on my browser, deleting the nonsensical babble forever and hopefully sparing all of you the headache of deciphering whatever the hell I was trying to convey.

I'm not trying to offend or flame, so please take what I say lightly. ;)

This sounds, like I said, insane. I don't have the scroll-saw, but I may make it, Snap-style and try it out.


I really like where this thought is going, however. Aside from the catch, It seems that this design concept could be (relatively) easily adapted to use prefabricated PVC parts.

#20 taerKitty

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Posted 08 June 2010 - 09:13 AM

why would you want to complicate everything by strapping it to the side of an inferior gun[...]?

To try something new, and see if its advantages outweigh the disadvantages.

Not to hijack Split's thread, so let's get back on topic: I love how simple the design is, how small it is, and how light it can be. I admire Split - he has high levels of craft, a willingness to devote a lot of himself to Nerfing, and (not least of all) a great workshop. He doesn't post purely to show off - he wants to contribute to the whole sport.

However, I'm pretty sure I can't duplicate this. I'm not Split, I don't have his skills, or resources. I'm using [k26] springs and not getting anywhere near his ranges. I hope to adapt his idea, the simplicity and elegance, but I need to be realistic in my expectations, hence my wanting to integrate it.

Whenever I make a rambling mess of words and incoherent thoughts that has barely anything to do with the original thread, I usually pause for a second with my cursor over the "Add Reply" button...

I just send a PM so there's less chance of threadjacking. ;)

Don't worry, admins I always take seriously, my friends I usually take seriously, and the rest, well...
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#21 Eh Watt

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Posted 08 June 2010 - 09:24 AM

I was planning on machining a +Bow this summer, but this has changed my mind! It's cheaper, easier and better in almost every way. It seems the only downside is without some sort of external stabilizer, you cant do much with the barrel besides a single hopper clip, because the coupler moves with the rest of the pump action... I'll see what I can do when I build mine. Also, it seems like it could stand a little more anchoring to the handle, but if you say it's stable, I'll take your word for it.

Stupendous job, Split, keep up the fantastic work. ;)

Edited by Eh_Watt?, 08 June 2010 - 09:26 AM.

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#22 MindWarrior

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Posted 10 June 2010 - 11:03 PM

How much would it cost in materials to machine one or two?
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#23 balisticjoe

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Posted 15 June 2010 - 04:13 PM

Split-I love this thing. A good project in between a snap and a +bow. I don't want to complain, but could you re-post the templates, they are sized weird in your pic. Thanks.
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#24 Lucian

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Posted 17 June 2010 - 05:03 PM

I'm surprised no one hasn't started their own yet, its so much easier then a +Bow to make!

Here's mine so far:
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#25 unTrained NERFER

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Posted 17 June 2010 - 05:33 PM

Split-Is there anyway you can get an internal pic of the maverick handle with the trigger? It would greatly help! Thanks
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