Upgrading my KWA VM4A1 2.5 aeg

Discussion in 'Gun Building, Modifications & Repairs' started by Bullpuper101, Nov 27, 2019.

  1. Bullpuper101

    Bullpuper101 New Member

    Hello friends I'm having a dilemma on upgrading my KWA aeg. It's a great gun straight out of the box but, I want more consistency and a bit more range. The problem I have found is KWA does not seem to be aftermarket parts friendly, mainly with the hop up unit and I believe air nozzle. I am going to give you the rundown of what I want to do, and hopefully this community can help me adjust some things.
    My ideal upgrade parts would be a PRO WIN M4 style rotary hop up unit, Prometheus purple bucking, Firefly namazu nub and a ORGA inner barrel. Yes this is to flat hop and I like the ORGA barrel because it does not require you to shave the bucking.
    With KWA the hop up unit is very slim so I fear I would be stuck using it, which is fine but can I change the nub? Also will this bucking and barrel still work with the proprietary unit? Just to clear this up now, my aeg does not have a two piece hop up it's all one, KWA seemed to fix that problem unlike older guns they made.
    Thank you for taking the time to read my thread, I am open to all suggestions.
  2. Guges Mk3

    Guges Mk3 Administrator Staff Member Administrator Supporting Member Lifetime Supporter

    What you are looking to do is rather dated, costly and not really beneficial for what you want it to do - consistency and range.

    Orga is iffy at best with HPA and putting it in an AEG will require more work to get more air into the barrel.

    The simplest way to get more range in your old KWA is the Maple leaf Packing and Nub. 15.00 and .28g bbs and your range and consistency will improve.
    Bullpuper101 likes this.

  3. aotsukisho

    aotsukisho Well-Known Member

    All of my experiences are with the KWA TK.45c, which uses a system a bit off the standard AEG2.5 spec so I'm not sure how much of this is applicable, but here's what I think.

    Hop unit is proprietary (TK.45's moreso) but spares can be gotten straight from KWA for $25. Older KWA M4s did have the two-piece hopup but anything I've seen past the Ronin line has the newer one piece design. Takes standard packings, nubs, and AEG barrels - I use a 300mm ZCI 6.02mm barrel in a G&G Green and I am happy with the performance. I've ran the Modify Ryusoku Baton flat hop before but I didn't like how it felt so I changed, might have had to use heavier bbs. Other packings I tried and fit well were cheap SHS soft split nub ones, stock Classic Army black, newer G&G blue split nub, and stock Krytac orange.

    I believe someone online got good sealing with the Retro Arms 21.4mm nozzle but you might want to read for yourself:


    My TK.45c's cylinder was a 75% M4 style design, overvolumed for the tiny stock inner barrel (217mm) but more balanced for the one I'm using now. If you are going widebore, then you may want to crack open the gearbox and swap it for a full cylinder...and if you are going to open it up, then you can do all the other good stuff like shimming (mine was actually good), AOE correction, O-ring swapping etc. I'm not sure how much of a difference it makes but my gearbox came with a flat, unported aluminum piston head so it doesn't expand the O-ring with air pressure but will make a nice even impact with the sorbothane/polyurethane/neoprene.

    Ran several motors before I opened up the gearbox for the first time, including JG Blue, ZCI High Torque (slightly out of spec, motor can is too long), and Rocket Airsoft 16t. I'm not sure what the stock gear ratio is (probably 18.whatever:1) but I did put in a 16:1 SHS set and spun then and they seem to mesh well so I think they can accept Marui compatible v2/v3 gearsets.

    Also of note is I'm not sure the Gate Titan is a drop-in like how they advertised for the TK.45 series and newer Ronins - A friend with the KWA G36C (Umarex licensed) got a Titan for his 2GX v3 gearbox and there was a lot of modification (dremeling) that needed to be done to fit it in, not to mention the instructions are geared towards an AK (G36 selector plate is on the opposite side so it's backwards). Not sure if you were planning on going this route but if you are then be aware. I was dealing with a lot of problematic cutoff levers around the time I was upgrading so I bought the Titan Basic specifically to avoid having to deal with them lol

    My TK.45 was running the longest with a 300mm barrel, G&G green packing, Rocket Airsoft 16t motor, Prometheus MS120SP spring flinging 0.25g at around 400fps. Stayed this way for about five or six months but now I suddenly lost a ton of fps so it's time to crack it open again, I suspect my sorbo pad gluing has failed.
    Bullpuper101 likes this.
  4. OrangeTJ

    OrangeTJ Member

    I have a KWA Ronin 6 (which is a VM4). I did just a simple change to a Tru Hop packing and got great results. It lifts .32s well with maybe 20% hop engagement and .4s with a bit more. Simple and inexpensive place to start, at least.
    Bullpuper101 likes this.
  5. Hyperslow556

    Hyperslow556 Active Member

    You have to measure nozzles before you think of buying a nozzle because they can have different lengths. When rebuilding my VM-4(R6), I can't remember what the measurement is offhand, but the Retro Arms nozzle is the same length and diameter, with a internal seal, and fit perfectly. I bought 3 nozzles before I figured that one.

    KWA's hop-up is rather good, but the bucking is not. The Pro-win Hop-up needs a little modification to work in the VM-4, though Maxx has a hop-up that was fit for KWA rifles. I don't see a reason for a different hop-up unless a person wants to integrate a tracer-unit into the hop-up.

    I'm using a Prometheus 6.03mm x 185mm inner barrel and Promy-Purple bucking. Works great!

    My consensus it that ORGA barrels are for sniper rifles.

    KWA is stilll using the 2-peice hop-up, just not on the VM4. The newer design of the 2-peice hop-up has been working rather well when listening to milsim enthusiast that "re-build" their new weapons.

    Best upgrade path: 1) barrel and bucking 2) compression rebuild 3) Advanced MOSFET(if not T6 Ronin) 4) high torque motor with supportive battery
    wetpee, Bullpuper101 and aotsukisho like this.