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JBU M120 Upgrade Kit for M4 AEG
[02969 / SDJA41]
Displaying 1 to 5 (of 5 reviews) Result Pages:  1 
by A. NIKNEJAD Date Added: Wednesday 04 November, 2009
For: JBU M120 Upgrade Kit for M4 AEG
Product Information:
I have been running this for a few months now, and everything seems great. The aluminum piston is a bit heavy for my setup and kills the ROF.
JBU did a good job, and my CA m4 was shooting over 400 and 800rpm with this, a EG1000 and an intellect 9.6v.
If you are on a budget (as I was at the time) try this, if not go for guarder or systema if you wish.

-Great quality
-Great value for money
-Smooth bearings in spring guide and piston head and smooth cylinder
-Good sized o-rings and overall good compression... no leaks besides where they should be

-Aluminum piston with steel teeth is completely unnecessary... get a polycarb piston instead like Guarder or G&P
-Not exactly a FULL tune up kit, more like a cylinder upgrade kit but whatever
-Lowers potential ROF a lot from stock form
by C. KIERNAN verified buyer Date Added: Friday 07 August, 2009
verified buyer
For: JBU M120 Upgrade Kit for M4 AEG
Product Information:
I bought this full tune up kit for my echo 1 m4. The guns loss almost all of it's compresstion in the internals. So I bought this, everything works great except the aluminium piston. The piston doesn't work right in my rifle. The teeth on it don't function well with the gun. I have heard this before for aluminium pistons and some other other things. I fixed this by putting in a polycarbonate piston it it worked great.

Cylnder is nicely crafted
cylinder head is nice
the air nossel has an O ring for increased comprestion.
Spring guide is heavy duty.
Spring is always a good thing.

The piston doesn't work in my echo 1
the piston head doesn't have a dish around the air holes
by R. LEW verified buyer Date Added: Monday 20 July, 2009
verified buyer
For: JBU M120 Upgrade Kit for M4 AEG
Product Information:
The JBU Tune up kit for m4 is a great way to gather the parts I needed for the start of a major upgrade. The aluminum nozzle, aluminum piston, aluminum piston head, aluminum cylinder head and chrome plated cylinder create superior compression compared to the stock plastic CA m15a4 cylinder internals. I just put my finger over the nozzle and slid the piston in and out to check. Changing these parts and the stock spring guide for a better one with ball bearings (included) prepared my aeg for stiffer springs. My CA m15a4 carbine has metal gears and metal bearings already. I added a Guarder SP100 spring (my field limit is 400FPS) and a 363mm Madbull Ver 2 tightbore barrel (6.03mm) to make my CA m15a4 carbine complete. It can now pierce an aluminum can through the center bottom (approx 385+ FPS). Be sure to have the cylinder grease, silicone lube, shims, tools, and patience to put it all back together if you plan on doing this yourself. A 9.6V battery pack is necessary to complete this project. My 8.4V pack just did not cut it. I highly recommend the video from mechbox.com on upgrading the spring for a version 2 gearbox as a guide for disassembly and reassembly of the gearbox. http://www.mechbox.com/mechbox/v2-mechbox-spring-upgrade.htm-

As the other reviewers have noted, the metal cylinder head, piston, and piston head make your gun louder with a crisp recoil sound.

These are very impressive, high quality metal parts for the price. I am breaking them in now and time will tell how well they perform in the long run.

High Quality Parts
Excellent Compression
Low Price
Nice Combo if you don't need gears or bushings
Great Upgrade for CA m15a4 series, the piston fits the rails
Fun project for airsoft-smiths and gearheads
Nice recoil sound (maybe a con if you want a silent head)

This kit would be better if it came with the cylinder lube.
There is no instruction sheet at all. I had to research all the info online.
This is not for someone that is unfamiliar with how the version 2 gearbox works.
Just don't plan on using a 8.4 V battery pack with this kit and stock gears/motor.
by B. SORNES verified buyer Date Added: Tuesday 31 March, 2009
verified buyer
For: JBU M120 Upgrade Kit for M4 AEG
Product Information:
Great kit and very good quality. I coupled this with a guarder sp140 spring and element 300% torque up gears and it fires with a stock battery and motor. If you're looking to upgrade to all metal internals this is definitly the way to go. It adds weight (which I liked) it adds kick (yes, the gun actually kicks after install) and it adds a nice sound over stock plastic internals.

Added Weight
Gun Kicks
Very Sturdy (dunno bout the longrun but after about 5000 rounds of testing still looks all new)
Everything is metal

The seal on the piston is a little finicky and takes time for it to start getting a full seal
The nozzle was sticking a bit at first so bb's weren't being fired consistantly
by L. MUNDERLOH verified buyer Date Added: Saturday 07 February, 2009
verified buyer
For: JBU M120 Upgrade Kit for M4 AEG
Product Information:
I just got this about a month ago and I must say the quality and look of this product is astounding! I almost didn't want to put it in my gun! When I set it next to the stock parts on my gun the difference was almost laughable, no comparison. I installed this in my ICS M4 and played my first skirmish with it today. I was very impressed. The gun shot fast and reliably. Some may see the aluminum piston as being a con since it slows your ROF, but it's barely noticeable. It just makes it more durable. Plus, the added weight of the aluminum piston coupled with the M120 spring gives your gun a bit more of a 'kick' feeling to it, making it feel more realistic. I would recommend this product to anyone!

Quality, you can tell just by looking and holding it that this thing was made well.
Aluminum piston
extremely durable
metal nozzle
gives a 'kick' feel to the gun

None as of this moment. Have to see how this kit holds up to the long term.
Displaying 1 to 5 (of 5 reviews) Result Pages:  1 
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