just a question
 

is there a gearbox kit anywhere that can get a TM m4 s system to 400 fps? if theres one and its on this site and you cant tell me which one as long as i know that there is one thats fine. on any other site then tell me which one. i know im underage right now but a 400 fps marui is what im aiming at. or another m4 with a lot of ris rails with a good fps.

400 FPS is a limit, not a goal....

stock mauri's tend to have solid internals, a stronger spring is in order...but really, dont focus on FPS, try range, accuracy, ROF, battery life...

That would be your battery, not your mechbox
And you will save yourself some money by just upgrading the stock TM, instead of buying a whole new mechbox.
Take a look around here

http://www.airsoftparts.ca/

Buy black BBs, you don't see them coming. Problem solved.

just pretend youre in the matrix

get a jg m4

Get metal bushings, a bearing spring guide, a sorbo pad, and the correct spring. You can upgrade a TM to high 300s without an issue. However, be aware that while the sorbo pad will help cushion and protect your mechbox, you still run a good risk of cracking the mechbox prematurely.

As for velocity, I say if you can hit 350-ish with a TM, you're doing pretty well and it doesn't need to go beyond that, at least from the mechbox perspective. Get a spring that will push 340-350. Then add a tighbore barreland you add 20-25 fps to that. And that will keep your mechbox safe.

upgrade the folowing for better gearbox: spring, shims and bushings, air nozzle, piston, bearing piston head, cylinder, cylinder nozzle, etc, pretty much all the internals. Its always good to stick to the same manufacturer for compatablity for your parts as well.

Before messing with the spring and risking breaking that already fragile gearbox, I'd see what a tightbore and a better piston head give me. Having a better seal is more productive fps wise IMO. It's not waisted upgrade anyway if it don't go as high as you want.

I also heard good thing about twist barrel. They are made for sub 350fps guns and some people reported very good range and crazy acuracy.

I'm considering one for my TM P90tr wich run at 350fps.

I just upgraded my TM AK with shims, bushings, 6.03 tightbore barrel, bearing piston head, cylinder head, 110 piano steel spring and it definetly made the gun more accurate and acheive higher FPS. These upgrades cost me around $100.

Want to learn about internals? Go to www.mechbox.com and watch some of their videos.

yep them twist barrels are a very wise investment and will add mad acuracy

I have a Tactical Force Tf16 and whenever I put it on full auto, it only shoots like 2 or 3 bbs, then just stops shooting. Is this because the gun is faulty, or is there sumtin I can fix?

what does that have to do with this thread?