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Internal Pump-Action Longshot (work in progress)

Now with more pics & rundown!

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#1 stoph

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Posted 28 October 2013 - 07:15 PM

Thank you to Carbon for being patient and reasonable, I'll try not to disappoint from now on.

Ahem. Take 2.

ACTION.

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Right, here's my current project - my take on an Internal Pump-Action Longshot. It's been the making for a little over a year, and is close to completion.

The Grip

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The grip was transplanted from a ShadowHawk 100 paper rifle. It was a fun toy but the ammo was annoying and was quickly shelved. I wanted to do something with it, especially given its lovely ergonomic design.

I retained the rail that the grip slides in, mounting it to a halved piece of 2mm styrene, before carving out a home for it in the LS shell itself. I used copious amounts of superglue and steel epoxy putty, as well as plastic welding in places, to fix the grip assembly to the shell. Its very very sturdy, with no give or flex. It helps that it doesn't take any of the actual strain of priming, as its a linear motion and the aluminium linkages bear all the weight of the beefcake spring.

The Linkages

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This took a good chunk of time to get right, with many small-yet-significant mistakes that saw me start again and again and again. We've all been there. If I were to do this again, I'd use polycarb for the grip interface plate, as its easier to machine. Don't ask for measurements, it's entirely dependent on your grip and where you've cut the shell, etc.

Anyway, the grip interface plate is 3mm alu plate, with some fairly precise drilled holes. This transfers the linear motion of the pump up to the alu arms (3mmx12mm flat bar). I used EMEUTIER's IPALS mod as inspiration for the alu tube spacers, adapting it where needed for my design. Everything is clamped together with some sturdy, slightly cut down M5 bolts. The nylock nuts had to be ground down as they were fouling on the shell.

There was flex occurring with the alu arms during early priming tests, so I added another M5 bolt to keep everything fron torquing out of shape. This was important, as when under load the arms splayed out and rubbed along the shell, making it impossible to prime right back.

The Boltsled

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I didnt want to fork out money on a polycarb OMW unit, and alu sleds are too costly. I ended up laminating thin, laser cut alu plates (available from Oznerfnerd) on the inside edges of the sled using JB Weld.

Before doing so, however, I drilled and tapped holes for 2 M4 grub screws on either side. I then drilled and tapped the end of the alu arms and screwed them to the boltsled. I used JB Weld in the threads to make a firm, nigh-unbreakable bond, effectively making the arms and the sled a single, solid piece. The alu plates help strengthen and hold it all together.

I used some 10mm right angle alu, steel putty and JB weld to reduce back and forth rocking between the bolt nub and the top of the sled.

The Back Plate

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Like the Frankenstein-esque boltsled (HA! Frankenstein bolts..) it's not gonna win any beauty awards, but it does the job. Its got speed holes to allow air travel in the plunger. It also serves the purpose of preventing flex from the high spring load. The small grooves in the edges line up with some interior walls so it holds everything in place when the shell is closed.

The Catch

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This polycarb catch is the latest addition. I wasn't happy with an alu catch I'd made, as it still had a lot of back and forth play. A small amount of dremmeling was needed to fit, but it wasnt far off.

This is, for all intents and purposes, identical to the stock catch, but almost twice the thickness. I ground a channel in the back top section to be identical thickness to the stock catch, so the stock plunger rod could still engage the catch. Note the second spring nub in the event of requiring double springing in future. Fits like a glove, still a smooth trigger pull. Also used a ground down screw as a spring-stay, as I had some issues with the spring bending double on itself and not catching.

The Breech

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The breech is a V3 Xplorer Fighter breech. Brilliant little kit. Unfortunately the alu barrel they sent with my kit was misthreaded and angling off around a half inch (bad!), but it gave me the excuse to rebarrel with my favourite barrel material, conduit.

Future mods will include:

- A silencer attachment to slow down the darts and let me use it at indoor wars with FPS limits.
- Torch in pump grip
- Locked stock
- Sling points
- paint job

Questions/comments/critiques always welcome!

Edited by stoph, 29 October 2013 - 07:54 AM.

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#2 Carbon

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Posted 28 October 2013 - 08:55 PM

Please don't make threads for "sneak peeks". If you want to show a preview of work in progress, you can post that in the Mods and Paintjobs thread, and then post a thread in Modifications when you have a writeup and pictures.

Edited by Carbon, 28 October 2013 - 11:10 PM.

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Hello. I am Indigo of the Rainbow Clan. You Nerfed my father. Prepare to die.


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