AK Brainstrust,
A friend of mine recently purchased one of these and is looking to pull it apart and check airseals etc.
I did find this thread on V3 upgrades which is very useful, from this and some other research the air seal parts and springs for V2 and V3 gearboxes are generally the interchangeable?
At the moment its getting around 260fps, we’re hoping to get closer to 300
260fps is pretty low for a Double Bell AK, even for the shorter one.
Not sure if they cheaped out on lower power/quality internals on the nylon shell/metal box versions as haven’t had one on the bench yet.
While have heard of their V2 box breaking the front off, haven’t seen it yet on the V3 though I do radius them and recommend it anyway if you are in there.
Parts wise, cylinder, piston, piston head, spring to suit is the easy option for power and reliability to suit.
Volume wise, all Double Bells have the same 70% cylinder. For these and 80% is more what it needs.
Seals, normally there is too much seal with their stupid double o-ring piston heads, or just loads of weight if it is their big thick single o-ring head. Now the metal versions generally did 330-360 fps ootb.
With the double o-ring head, dropping to an m90 to get it closer to 300fps completely stuffs it, will have much lower fps as the spring doesnt overcome the huge amount of friction of the double o-ring piston head.
Their piston also has their own size hole that doesn’t suit most normal heads.
So changing the piston and piston head is recommended. Good quality piston that suits the box, and a nice normal flat faced single o-ring piston head is much better.
Now you have the right volume, and a seal with optimal free movement to just pick the spring that suits you fps requirements.
Nozzles for double bells… you’re screwed and stuck with what they have. Unless you are prepared to do some work!
Watch my double bell PDW part 2 video for details, but where it mounts to the tappet plate and the nozzle throat is similar to LDT, but the tip is similar to a Jin Ming but shorter.
I used an LDT nozzle, and the stock nozzle tip cut down slightly with heatshrink to fill the void between nozzle and tip. Worth noting, heatshrink has worked so far, but I suspect it may cause nozzle tips coming off at some point. Nozzles do get warm with use, so finding something better is ideal, I just haven’t looked into it further as so far it has worked for me.
Can I also suggest, if your friends DB came with a metal magazine, that he purchase a few of these nylon ones from AKGelblaster. The metal ones have a history of snapping the front retaining clip unless very careful. These ones are cross-model compliant and from what I understand, do not share the same issue. Please note the comments on the product link below that some minor filing may be needed to fit the DB.
Sorry @RokSolid I had a reply written but didn’t hit the reply button.
Very helpful post thanks, as always.
He’s ordered some bits and pieces which are slowly arriving so we’ll get into in soon.
For reference he bought the same blaster around 6 months ago and it was doing 300fps, it was also incredibly accurate. Because of that he bought a second as a backup however it was only doing 260fps under the same conditions with the same gels.
