Building a TKB-022PM (Ruski-bullpup!)

[Grounded_Pilot]

Firstly:

Haters gonna hate!
*Posts along the lines of "Why would you build such a fugly gun?" are totally irrelevant. I'm building it for reasons why I hate the common platforms out there, and to prove my ability as a tech!*

Now, the project.
I saw this rifle while casually familiarising myself on world.guns.ru. with weaponary new and old.

I loved the idea of a bullpup AK type build- I am a huge bullpup fan!

However, the PM variant stood out most of all for me- and also happens to be the most difficult to make... at least with only basic materials, skill and tools!

Here's the real thing (courtesy of world.guns.ru)


Yes, it's absolutely, positively, 100% fecking... wonderful. Just look at that crazy design. Imagine actually firing that... so I set about making a draft plan (on good old MS Paint) to come up with a basic design using parts I had lying around (images from my computer will be smaller, sorry, click/hover on them to make bigger):
tkb022_Left_innerdiag.jpg

I noticed I could at least make a Look-a-like with AK parts, the rear sight, mag of course, pistol grip, trigger, and even the front sight to an extent.

I even had an idea for the selector, drawn (several drawings):
Selector1.jpgSelector5.jpgSelector2.jpgSelector3.jpgSelector4.jpg
Idea was to have it attached to a hinged plate, attached to the original AK selector plate. So as you pulled the selector down, you'd push the selector across. This would result in the wrong order of firing however (Safe, Auto, Semi) when the rifle used a typical Safe, Semi, Auto select you see much more commonly.

Now, here's what I have for the internals. Using a 10mm overall width PVC piping (8mm internal diameter) to act as a feed tube between hop unit 1 and 2, I have made the bridge.

I also have the V3 gearbox and motor, working and ready to roll.

I cut in half a Plastic bodied Double Eagle M900E (tacticool Ak47) for the rear magwell.

I have made mods to the front sight so I can actually adjust the hop unit! Pretty impressed with my ingenuity!

Now, where I am at current:
(NB: The total cost for this project has been virtually NIL. I had a broken gun and spare parts galore lying around. I paid like £2 posted for 1M of PVC tubing from a particular bidding website)

20140315_132001.jpg20140315_131953.jpg20140315_132007.jpg
(...annnnndd that's my max pic limit.)

Also, contrary to popular belief, this thing does work and fires BBs with as much accuracy/range as any other AEG Despite the laughably short barrel!

Where I am now stuck:
-Feeding!
AAAAAAAAAAAAAHHHHHHHHHHHHhhhhhhhhhhhhhhhhhhhhhhhh! *Internal screaming*

I have figured (to my dismay) that none of the Hi-caps I have, possess enough power to force the BBs up reliably (a fair bit of weight). I recon a Mid Cap might be better, but still probably not enough... even so, I do not have one to experiment with!!
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SO! If you have an AK mid cap to sell, or know a novel way to increase the feeding power of a hi-cap, I would greatly appreciate your comments!!

Once I get the feeding done and dusted, I shall begin properly arranging the parts for bolting in place (make a skeleton structure), before covering in chicken wire, papiermashe'ing a body and then melting polymer over it to form the externals!

...That's the plan at least! If you have an different battle plan, please let me know!

[Mango]

Re: Building a TKB-022PM (Ruski-bullpup!)

Can't you just have the hop @ the back then the barrel go through the whole gun

[Grounded_Pilot]

Re: Building a TKB-022PM (Ruski-bullpup!)

I would have loved to do that, but I see no way (without at least some clever mechanical system of unique design) to power the BBs forwards if the mag is literally at the back!

[Xxerox]

Re: Building a TKB-022PM (Ruski-bullpup!)

Yeah, my first thought would be to connect the gearbox to the back of the hop at the back of the gun using the PVC tubing - as long as you seal it tight and no tight bends it should be ok?
That long PVC tubing filled with BBs - even a good mid-cap will struggle and you'll cut the capacity down to virtually nothing - I'm betting there's a good 20-30 BBs in that length?
Difficult one for sure as there's so little space behind the mag!
Looks interesting tho - not sure about the paint job on the ref pic :P

*EDIT*
Having just said that, I realise that the nozzle is the bit which physically pushes the BB into the hop...
Fail

How does the real one do it? Am I right thinking that the bolt on a real rifle still generally moves a way behind the mag to pick up the next round?

[Mango]

Re: Building a TKB-022PM (Ruski-bullpup!)

Maybe you could use something like LMGs use where they have that feed tube from a box mag

[Grounded_Pilot]

Re: Building a TKB-022PM (Ruski-bullpup!)

Yeah, my first thought would be to connect the gearbox to the back of the hop at the back of the gun using the PVC tubing - as long as you seal it tight and no tight bends it should be ok?
That long PVC tubing filled with BBs - even a good mid-cap will struggle and you'll cut the capacity down to virtually nothing - I'm betting there's a good 20-30 BBs in that length?
Difficult one for sure as there's so little space behind the mag!
Looks interesting tho - not sure about the paint job on the ref pic :P

*EDIT*
Having just said that, I realise that the nozzle is the bit which physically pushes the BB into the hop...
Fail

Yeah, Unless i can get some PVC tubing to connect from the cylinder, to then cycle air to the rear, with the nozzle attached, but still able to be tappet affected.... oh my gosh, I can see specialist sector gears, a rear facing and/or extended tappet plate and more just to make the barrel m16 length and to aid feeding.

Hahaha 20-30 rounds? I think it's nearing 100 BBs at one time in the tubing!

Maybe you could use something like LMGs use where they have that feed tube from a box mag

I just hoped I could make it similar to how a drum/box mag feeds, with those odd spring tubes. Just this is TOO long I think...

Paint job is odd... two tone? xD And it's ABS plastic too- which is very-non Russian. Maybe it was just Plastic for the prototype, and intended to be wood- hence the odd paintjob!

- - - Updated - - -

One of my other options is to use a gearbox (maybe an M249?) that can sit further back and thus shorten the length of the tubing...

[Xxerox]

Re: Building a TKB-022PM (Ruski-bullpup!)

100?! LMAO - good luck with that then. Most mid caps are around the 80-120rnd mark, and jamming 120 rnds into a mid-cap generally gives poor feeding for the first 20 or so, so you'll get 20 rounds of poor feeding per mag :P

In seriousness though - wondering if you could do something with a tappet and nozzle set up at the back...
You know the gearboxes with holes in the top for "electric blow back" - wondering if you could connect a custom made tappet into that and have the nozzle right at the back - then you can have the hop directly on the mag, a barrel through the whole gun and use the PVC tubing to transfer the air from the gearbox to the back of the barrel (would mean you wouldn't need the nozzle or tappet plate IN the gearbox as well...

[jonny lovegrove]

Re: Building a TKB-022PM (Ruski-bullpup!)

Get an electric feeding mag.

[Mango]

Re: Building a TKB-022PM (Ruski-bullpup!)

Are you going to make the body?

[G33m4N]

Re: Building a TKB-022PM (Ruski-bullpup!)

Meet the Hephaestus HTS-14 GBB -http://www.hephaestusairsoft.com/ind...&product_id=85

[bob86]

Re: Building a TKB-022PM (Ruski-bullpup!)

why dont you use a 249 gearbox with its hop unit, sit it right at the back of the body? the bbs wont have as far to travel then, and you get a longer barrel if you want it. you can just wire up a trigger wherever you want it, hell you can still use that ak body at the front if you wanted for the trigger and pistol grip, you just run the barrel thru the empty gb shell

[Grounded_Pilot]

Re: Building a TKB-022PM (Ruski-bullpup!)

In seriousness though - wondering if you could do something with a tappet and nozzle set up at the back...
You know the gearboxes with holes in the top for "electric blow back" - wondering if you could connect a custom made tappet into that and have the nozzle right at the back - then you can have the hop directly on the mag, a barrel through the whole gun and use the PVC tubing to transfer the air from the gearbox to the back of the barrel (would mean you wouldn't need the nozzle or tappet plate IN the gearbox as well...

That is an idea I had considered, but I might have to put the sector chip elsewhere on the gear... yano, as the feeding cycle will be backwards if the nozzle is BEHIND the gearbox!

Get an electric feeding mag.

Do they have more feeding power than a regular hi-cap? I assumed they were just easier to use than stronger...!

Are you going to make the body?

Yes... I am. I'll try dammit! Probably will be crude, but the main object of this project is to build a bullpup AK!

Meet the Hephaestus HTS-14 GBB -http://www.hephaestusairsoft.com/ind...&product_id=85

I shall contact them, I personally hate GBBRs but would be nice to hear their thoughts! I do like what they've done already!

why dont you use a 249 gearbox with its hop unit, sit it right at the back of the body? the bbs wont have as far to travel then, and you get a longer barrel if you want it. you can just wire up a trigger wherever you want it, hell you can still use that ak body at the front if you wanted for the trigger and pistol grip, you just run the barrel thru the empty gb shell

I think bob, this is my next logical step. I have been considering that seeing as the body of the gun is clearly large enough to house a "block type" gearbox...! It will shorten my feed tube length... maybe if I buy a broken one I can get the box mag parts from it too...

Any further suggestions? xD

[Xxerox]

Re: Building a TKB-022PM (Ruski-bullpup!)

If you can shorten the feed-tube a bit, then I would imagine an electric drum mag mech would be able to cope - after all, the support gunners have probably a 20-30 round feed tube...
With the AK mag, you can get the bigger ones which I believe can take 1000+ rnds? (or custom make one - essentially a box mag for the gun which just happens to look like an AK mag - and if you're really stuck for space after fitting the mech, you could always put some of the BB reservoir inside the gun as well) - would mean you couldn't really use it during Mil-Sims, but for your average skirmish, would be fine.

[Darkmikey22]

Re: Building a TKB-022PM (Ruski-bullpup!)

An auto winding ak drum mag would be fine for this and would push the bb's as far as it needs too.
The only issue I could see with this is, even though you take the mag out you don't know if all the bb's have left the internal tube. so with no way of checking in theory you would be entering a safe zone with a hot weapon. yes you could tip it forward and upside down, but I do that with my support weapons, yet still bb's appear from somewhere, which is why support weapons are usually left outside the safezone.

[Xxerox]

Re: Building a TKB-022PM (Ruski-bullpup!)

Perhaps a a physical cover for both muzzle and trigger might be a good idea with it then. Muzzle is easy enough, and given the shape of the space for the trigger I imagine you could form a slide on cover for it.