Better spring for my TM mp5K.

[FireBird]

What is the biggest spring i can put in my mp5k without causing the gears, motor or battery to burn up. And without the rpm to go way to low(considering the biggest battery I can put in is 8.4v).

[Newman]

Well, nothing will ever "burn up", per se.  That just doesn't happen.  Using a bigger battery could somehow burn some crap up, but not using a new spring.

I can tell you from experience that my mini batteries (8.4v 600 mAH) could not handle my 150% very well at all. I really doubt that a mini 8.4 coud handle a 140% very well either, so maybe a PDI 130% or lower?  That would probably make sense.  Remember, when you upgrade the spring, the ROF will go down, regardless.  You need a really high-amperage (mAh) 8.4 volt battery or a 9.6 volt battery to keep ROF up there with a stronger spring.  Good luck, dude.

[FireBird]

Thanks a lot. Do you know what spring is in the gun right now?

[Newman]

Typically in a TM, an M90 (am I correct Airsoft gurus?).  That's not a %, it a meters per second equivalent, so it's 90 meters a second=270-285 feet per second.  The percent kind (like my 150%) is PDI, they are easier to install but the power wears down over time to a lower fps but usually stays there.  The M type are more "dense", so as to say, and are harder to put in, but usually stay at their rated speed.

[Bigmack]

it works out like this:

the 'M' series by Systema works by giving you the speed in meters per second...
M90, the standard spring, is 90 meters a second..or about 270-280 FPS...
M100 is 300..
M110 is 330...


the PDI springs...are measured like this...
100% is equal to the stock spring...   100%=M90.
150% is 50% stronger than the stock...
200% is 100% stronger than the stock...

[Locutus]

Whoa guys, slow down.

An m100 will put you at about 350 fps. I have never heard of an m110 spring, and a m120 will put you up around 380-390fps. Of course this is assuming you are using .2g BBs.

As far as the PDI springs, not sure what the % is based on, but if it were based on the stock spring, than that would put a 300% spring up around 800fps, when in reality it is right around 500fps.

[DUNCAN]

yeah, I agree with locutus on the Systema M100, I heard it is as tough as a PDI 140%, and I also put one in my AK, and the rate of fire has severely dropped, still being usable with my 8.4v stick battery though.

Also, with the percent springs, I do believe that they might be that more percentage of power added to the spring, like the 200% is 100% more power than the 100%.  The only problem is, when bbs get to the faster speeds, they need a larger amount of power increase to actually make them go faster.  The bbs have a large amount of wind resistence when they are going 100s and 100s of fps, and their weight is so small that they only have a miniscule amount of inertia, so they slow down very fast.  At higher speeds, ofcourse, there is going to be a much larger amount of wind resistence, and somewhere, those bbs are going to have a kind of terminal velocity. The bbs could never get up to 800fps, or even 600fps at that, from any airsoft gun with any spring.

[Bigmack]

i can't find the guy's site now...but a few months back, i was looking at a guy in California's site...

a custom spring he had made...he called it an M190...but they dont' make them that fast..., reinforced gearbox, hi torque gearset, EG1000, bore up cylinder,  tightbore barrel...and he was chronoing at 670ish.

[FireBird]

So with all this FPS debate, what is the biggest spring(M and %) I can put in without going over AO limits?


Edit- without going over the AO limit using .25's

[DUNCAN]

Jeez, I didn't think anyone would be that crazy and try to shoot that fast, but still an M190 is still supposedly tougher than a 300%, and hopefully nobody in their right mind goes quite that high, unless they stay far away from me.  Ouch, 670fps!!

[Chewcky]

um does that mean that it will break the skin  

[Bigmack]

easily.  the guy used it to kill small animals around his property...  crows, squirels, rabbits....  he used those darts that one of the companies made a while back... (Marushin?) ...and he had to take the hopup out...be cause after only a few rounds, he had destroyed his hopup assembly.
he dropped the darts down the barrel individually...and he used a .22 sight...and the markings were almost dead on out to 50 yards.

the extreme upgrades like this can make airsoft quite deadly.  I'm sure that this puppy would have shot right through any paintball masks or tactical masks that we all carry.  

[Robo]

definatly defeats the purpose of airsoft.........

[Newman]

Hehe, that's why the guy didn't use it for playing Airsoft. I'm guessing he bought that and not a regular bb gun because, either A: metallic bb guns are illegal where he lives or B: because it's full auto.  Didn't he buy a 16.something volt battery to power that thing full auto?  That would kill big wabbits. ;D

[Locutus]

firebird, if you want to retain your full auto capability, the maximum spring you can use is the m120 (or pdi 170%), anything above that you are restricted to semi auto only. The maximum spring you can use is an m150 (or pdi 270%).