First time Mechbox takedown - Version 3

[venture]

Well I have had this Tokyo Marui MP5K PDW for over 4 years now. It was well used when I bought it and I have probably put 20000-25000 bbs through the little gem. Still works great. ROF is through the roof at 950 RPM now. It was about 650 when I bought it in 2005. The spring has weakened that much over the years. I bought a chrono this year and the thing shoots 240 fps with .20g bbs and about 210-215 with .25g bbs.


Well I figure that this winter I will lose my mechbox virginity and get inside my first box. I will open the mechbox and who knows what I will see. Surely some parts will be worn.

I am counting on needing shims, bushings, piston, piston head, spring, and spring guide. I would like ask advice about other things that may need replacing.

Obviously, I will check and replace worn and broken parts, but other than what is stated above is there anything else that I should replace outright?

I see full tune-up kits available but none for the PDW. If I got one for another ver. 3 model can I use it?

I want to keep it about 110% of stock power. Is that what is called an "M100" spring?
If the gears are not worn, can I keep them or should I replace?
What gear ratio should I get?
Should I replace the cylinder?

I have a 120mm silencer. The PDW barrel is 141mm. Can I use a G36 barrel at 247mm with the stock cylinder? What type cylinder should I use for that barrel length?

I don't want to take apart my baby until I am confident I know what I am doing so I would like to get some of these questions out of the way first.

If you can think of anything else please let me know.

[L473ncy]

Depends on what brand of spring you get since the nomenclature might be the same but the actual outputs may be different, check the ASC spring chart and other websites as to what speed you'll get. M100 or M110 sounds like what you want though.

I believe you can use FTK's for different models however with the caveat that you may not get the right parts for your gun (eg. the kit is for a V3 gearbox however the cylinder might be for a longer or shorter gun that what you have).

I don't think gear ratios matter too much with a low FPS setup like what you have but I'd go with a set of high torque gears or standard gears.

Ehhh that's about right for length, although you'll probably need to change the cylinder (if you get an FTK just get a set that includes a cylinder for a longer barrel).

[venture]

Thanks, Latency. Good answers as usual.

[Con Murder]

You should add metal bushings to parts list as TM is plastic stock. Also V3 parts should all fit as they are made TM compatable mostly.

If you get an upgrade kit that has ported cylinder for PTW and you wannna go 247mm I can ship you the right cylinder as my SIG 552 was 247mm before I changed it up.

[theguy]

You say you want to keep it 110% of its stock power, So, 300ish?

I recommend a modify s90 spring from airsoftparts.ca

In fact, I recommend buying all modify parts, They make great parts for very reasonable prices, and can be found in canada

As for the barrel question. Although a tightbore is a good idea for sure, theres debate whether or not a longer barrel actually adds accuracy. If I were you, I would stick with the stock length, in case you ever decide to ditch the silencer. However, if you did want to go with a G36c length, i belive you would need a type 2 ported cylinder (again, i recommend modify parts from airsoftparts.ca)

TM gears are notorious for breaking with anything more then an 8.4, they are defiantly a weak point on stock TM guns, So they probably would be worth looking into replacements for.

If you want my oppinion, Look into a modify SMOOTH full tune up kit from airsoftparts.ca, They are pricey, but include a fantastic amount of great parts, including self-shimming gears!

You don't need an MP5 specific kit, just make sure you get a V3 kit (probably AK or G36)
You will need to still use your stock selector plate, or buy a new one.

Last but not least, if you do decide to go down the SMOOTH FTK route, I wouldn't recommend using the spring that comes with it. I would still recomend a modify S90.

Hope that sheds some light on your situation, and sorry for writing that much :P

Best of luck with your project,
-Ben


EDIT:

Also! If you havn't already, check out mechbox.com, lots of great videos for basic V3 maintenance and upgrades

[venture]

Thanks all for the help. Advice has been great.