AK DMR

[Redfire]

I have been thinking about converting my G&G RK 74 T for DMR for a while. Recently my MOSFET has failed so would like to know if anyone can recommend a decent option to replace it with active braking and single shot only option.

 

I have replaced the spring, hop and barrel already but would like to know what the best options are for other upgrades. 

 

Thanks 

[Sitting Duck]

If you are going to DMR 425-450 fps you should not need AB mosfet I would have thought

With a M130 spring you won't get lots of overspin and what you might get on 11.1v will be pre-cocking

 

usually the selector plate mod or the dis-engage of part of linkage will give you semi only

if using a mosfet - then consider placing a tiny micro switch - tactile 6mm micro switch somewhere

wired in as a positive supply to mosfet signal - effectively another trigger switch

tucked away neatly - to be used should you ever have a lock up and need to clear or cycle gun (mag out)

saves a gearbox strip down on a locked DMR should it ever happen

 

Really think people need not spend loads on bells n whistle stuff

you get a basic mosfet on there to protect contacts, run on 11.1v or something if you need

add lock up switch - job done

 

Worried about leaving spring pre-cocked - fire on lame or low charge 7.4v before storing

 

I mean fancy high end mosfets you can config to fire only once or semi only

and if required a delay between shots of say 30 seconds but never heard of sites demanding that

maybe the more mil-sim sites might require this 20-30 sec delay to stop twats semi spamming DMR's

but so far not seen this ruling though I'm no sniper/marksman - I'm just cannon fodder decoy for the rest of team

[Redfire]

Thanks for the in depth reply. I have disengaged part of the selector mech. I was only going to run m120 spring but maybe in the future I'll move up a level.

 

I would prefer to run it without MOSFET but it had one from stock and also etu . Is it possible to run the g&g etu without a MOSFET ? I will be R-hopping next week so plenty to read up on... 

 

I have been having an issue with the gearbox over spinning consistently single single single double etc. I don't suppose anyone has a clue? Iv taken it to various local techs and everyone says something different, most recent says crappy g&g MOSFET.

[Sitting Duck]

Ahhhh - ETU, pretty sure it isn't an AB mosfet hence the overspin

No doubt you have to run on a very good 9.6v or 11.1v

You probably got a Blue Powerful motor or if lucky the Orange Ifrit

which on 11.1v with a m100 you would get a bit of overspin

 

Not had any experience with v3 ETU's but I'd tend to agree with most that the unit is a bit crap or at least mehhhhh

 

I had a FFR A2 which didn't like messing with more oomph faster motor and blew so had to convert back to old trigger

IF......

and it is a big IF the v3 is like the v2 then it is likely you will need a new v3 trigger - no biggy

you will also need the trigger trolley spring and also a new selector plate - but you won't perhaps...

Reason why you need a new selector plate is coz the plate is cut to NOT lift the Cut Off Lever for auto

The v2 selector plate in my FFR was cut for semi only as the tiny micro switches at back of ETU told mosfet to fire semi/auto

Being that you are considering DMR then you would need auto so could keep old semi only selector plate at a push

 

The reason why it overspins is coz the longer barrel in a AK only needs a m100 or even a m95 to hit 345fps

On that light spring on higher juice with a half decent motor it will overspin a bit

Hence G&G say keep the 11.1v to only 20c, a higher burst will spin more especially on m95 etc.....

 

I'd go to a m120 or m125 max as the longer barrel will creep a bit more than expected 400 fps if seals are good

However - the ETU's durability is a bit like Dairy Lea so it might not like the heavier spring

BUT the m120/125 spring will slow the piston retraction reducing the overspin

Also the higher spring producing the higher fps will return the piston on release quicker helping to avoid PME

BLAH BLAH BLAH....

 

The real question is - will the ETU last or hold up OK - answer: fuctifino

 

Yes you can run the gun quite nicely with a m120/125 but as I said will the ETU crap out

tbh if it does crap out then it is no biggie - poxy thing anyway

 

 

The vids show you can make an AK47 run quick but not at 345fps - you need a stronger spring to return piston quicker

or you short stroke to avoid PME but you can't SS an AK47 coz you need nigh a full stroke for volume

So you have a problem with the ETU liking more juice to work properly but causing overspin

 

You can try to use 9.6v nimah or a 9.9v LiFe but some have found as soon as the juice drops a little the ETU plays up

Or a mild 15c to 20c max 11.1v - what C rating is your present battery ???

[Sitting Duck]

Small update suggestion perhaps....

 

If you have a good beefier motor - blue powerful or orange ifrit which are about 25,000rpm

perhaps get a lame ar$e grey 18k motor which is quite crap but on 11.1v should be ok

Should be able to get a crappy short 18k grey motor quite cheaply as people chuck these as they upgrade

worth a look on fleabay perhaps - a cheapy higher but slower tpa motor should be about I would have thought

 

Let us know how you get on, I might have a crappy short stock motor or two knocking about

dunno what the spec is but no doubt crap so should be slower than your present whippy motor atm

[Hangtight]

If you want great semi auto trigger response with basic internals then consider a BTC Chimera and use the pre cocking. Set it to pre cock at the semi auto selector position and single shot without pre cocking at full auto so you can release the spring compression.

But for a kicking DMR set up in V3 gearbox, 7.4v, 22TPA motor and 13:1 gears with the Chimera. That'll pull a 130 spring with ease. Add a nice heavy piston and you're golden.

[Redfire]

That's a lot of great help - thanks. For the time being I just replaced the stock MOSFET and all is well with the new spring, I will change the gears and motors next, no halm in doing the piston/cylinder too. Great forum guys - thanks again!