Nope…not happy with pinkies.
Lots of blow ups…it seems to like the harder gels… maybe they survive the longer barrel better.
Also, even without the chrono…variable fps…
Some go fast, some dont go far at all…
A thorough investigation would be required…
I’d do what Doc suggest…
Check that barrel insertion, for sure. Exploding gels is a dead giveaway that something isn’t right there. 
Also, think about making up a spring and plate for the mag, solve all your feeding issues. Maybe check if a P90 mag spring and follower would work with some modification. Wouldn’t be difficult.
I double checked, before i resin-ed the barrel into the t piece.
It went all the home, with a “thunk”
I marked it , with a line.
It feeds the harder ihobby blues a lot better…no exploding.
Hmmm…
Alignment is key too. It’s got to be straight from back to the tip.
Funny about throw some cash around 
I just chuck it all up in the air and see what falls out 
With that low FPS it should feed the medium hardness gels like pinks no problem. I’m surprised it feeds the harder iHobby gels without jamming being so low powered.
Gotta be a t piece problem… maybe even the mag feedwheel cutting up the softer gels a bit before they even make it to the t piece.
Trial and error… eliminate one possible cause at a time until you find the culprit. 
I was looking at these last year just after I started getting into gelsoft, my idea for it was to just tape a 3ltr milk bottle with a speed loader nozzle to the magazine…
“Suppressing fire!!!” 
Call you up for fire support anyday
id love to get mine working again, tpiece snapped and nozzle broke so it no longer connects to the cylinder head.
obviously both of these are nearly unobtanium so its now just a display piece 
$290 from gbu, for a whole new kit…
or ihobby will price match,
if you really, really want a working one…
Considering the expected performance and physical impracticality of these units, I’d be keeping it as a non-functioning static prop if I had a broken one. About all it’s really good for… if you’re going to be honest.
A lot of dosh and work for something you’re not likely to run around a field with. Then again, I also get the OCD factor whereby if you got it, it has to work. 
Something I suffer from and I’m trying hard to get away from. I’m okay with non-functioning props these days.
But that’s just like my opinion, man… ya know.
Never got to take mine to a game, as arrived right in the middle of the Bans were being announced after a month of waiting for it to arrive , being ordered before the Bans were ever even mentioned to the public. 
There’s a 2 story Wooden Fort at one of our fields, and the idea was to be able to up the ante when we played “defend the Fort” games by getting it set high up on the corner, which is very protected by the height above the attacking team and gives a wide field of fire. 
Would I run around in the scrub and trenches with one… HELL NO!
Might be handy for Pole Vaulting over defence barricades though? 
Excuse my shabby laziness at not editing these screenshots, but just wanted to show that these were the closest cylinder head/nozzle designs to the ZB26, but never got the chance to order some and trial them out. 
I used to get a fair bit of gear from Airsoft Tiger 111HK and is where I first came across these Airsoft V6/V7 type systems.
The nozzles have a half moon ground off the upper surface to allow clearance to operate on the outlet tube, looking a bit weird, but in reality, I’m sure that any nozzle could be ground down to the right shape to be able to fit.
A few notes, for future reference for others…
Be Super careful with the t-pieces…they are Very fragile.
FULL LENGTH SEATING:
if your barrel is requiring a lot of force, into the fragile t-piece, soak the tpiece in some just boiled water. This will soften it, and it will go on/off with a lot less force, to the full length, without risk out snapping the tpiece.
Epoxy will seal it later.
The screw in sides are very thin, and break easily…
Before warranty return…
They shouldn’t break, with the force required to seat it properly…
Finally…Resin Reinforcement.
Even with all that, grab the T-piece buy its thicker body, when pushing it down.
Avoid pushing via the top.
I heard a tiny “Crick!”…hairline crack.
Thankfully loads of epoxy on hand, it got 2 good , seperate coats.
It is now airtight ( blow test), and ill let it harden several hours, before giving it a try…
Moral of the story…Beware of the T-piece…!!
Should have been made of metal, being so thin…
Might pay to reduce the OD of the barrel slightly too…
Good practice to see how much of an interference fit you have with proprietry plastic parts.
Little progress made on @BME ZB.26
Loved the welcome message!
And the other side had helpful and playful messages!
It’s open!
And yes there is provisions for a cut off lever setup but was never installed… you could likely have semi auto if you wanted, even add an ETU? Options that were never explored in the factory for some reason.
Gears are standard cast affair. Piston has a cast rack, with aoe correction spacer behind the piston head. Normally not a bad idea but when the volume is so desired for the monstrously long barrel the extra 2mm of piston travel would be more beneficial.
Cylinder head sealed decently but o-ring was munted.
These bearings are not great for stiffer springs,
So out they go for some solid slim bushes. Now there is room for some shimming!
Motor looks like similar to wells spec but with a decent tower and pinion… albeit they didn’t bother with a grub screw!
New POM piston with a tough rack that has been super strength epoxied in, and a nice flat alloy piston head should give a little extra weight to help push the gel down the long barrel.
Green o-ring on a green head of course!
Things I didn’t get photos of…
Replaced the cylinder head o-ring. The stock nozzle actually seals alright, which is fortunate as it is very much proprietary!
Shimmed the gears… then ran out of time for the moment!
Just needs a good clean and lube, and assemble and see how it goes with the long barrel, I suspect we might need to trim it down a little to bring the consistency and maybe fps up, but we will see!
And yes there is a video of everything
Looking good…!!
Photo 2 has a little glare on it…
The message says… " Death To Squiddy !"
just so you know, its a BME box…!!
I suspect you will be working on a few more nylon boxes, in the near future…!!
Funny, I had one of these gearboxes pulled down just yesterday afternoon. 
Were there any shims in place on your initial teardown? The one I disassembled yesterday had what looked like factory shimming in place.
Distinct lack of grease however.
Oh yeah there was grease, not much on the gears but that sticky oily type everywhere else.
And shims. One on each gear. All gears only spun as they were in bearings!
Not a bad box to tinker with though.
