Review: JBU M4 Free Float Hand Guard Kit (F8A)
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I was asked to review this conversion kit by the guys at TSD Tactical. JBU is fairly new to the custom market, and they are eager to get their products noticed.
Unlike most kits, the JBU kit does not ship in a flashy box; instead it is a nondescript brown box with a tiny green sticker. The kit comes with a delta ring, barrel mount, tight bore barrel, free-float handguard, flash-hider, one piece outer barrel, front sight, and a delta ring wrench.
The parts are made from three different metals. The outer barrel, tight-bore, barrel mount, handguard and delta ring are made from aluminum. The flash hider and front sight are made from pot metal of some sort, and the front sight retaining pins are made from steel.
Fit and finish
The parts all look great with the exception of the front sight, which has a different, more uneven, finish on it. The other parts all match in color perfectly, and the finish is as smooth as satin. You'll notice in the pictures that the outer barrels' finish is all jacked up, I've taken the kit on and off around 2 dozen times, and that wear is the result.
The handguard itself is not much more than a tube with threads on one end and some very well done checkering on its mid section. The checkering feels very nice, and once assembled the entire unit feels great in your hand and very sturdy.
The chief flaw with the JBU kit is that the handguard is too skinny to accommodate a normal mini battery, or even a two-brick style nun chuck battery.
The JBU tight-bore is made from aluminum, and is given an external coating. The business end is chamfered inward to provide a clean leading edge. JBU also engraves their website address on the barrel.
Accuracy from the tight-bore is superb, with shots landing one on top of each other at 80 feet; even in full automatic.
Below are the instructions for installing the JBU kit. You will need a few simple tools to get the job done: Hammer, punch, 1.5 mm Allen wrench, slotted and Phillips style screwdrivers, a knife or an eyeglass screwdriver (something thin and fairly pointed). You may also need a file.
Before working on any Airsoft gun, always remove the magazine turn the hop-up off, and remove the battery.
The first step is to teardown your M4 or M16 or what have you. You only need to go far enough to remove the hop-up and barrel.
Once the barrel is out, separate it from the hop-up. First remove the C-Clip with a knife or eye glass screw driver, then slide the barrel out of the hop-up chamber.
With the hop-up and barrel separated, remove the bucking from the barrel, and put it on the new JBU barrel.
Reassemble the hop-up and put the gun back together.
With the tight-bore installed, we can move on to the handguard itself.
Begin by pulling off the handguards and removing the front half of the wiring system (if you happen to have a front wired gun).
Next you remove the delta ring to release the barrel; there are two ways to do this.
The first is by simply rotating the ring until it begins to unthread from the front of the upper receiver. The second involves disassembling the delta ring, and using a screwdriver to begin rotating it. Either way, once the ring is loose, you can remove the outer barrel.
With the barrel off, go ahead and remove the front sling hook, you'll need it on the new JBU front sight, as one is not included in the kit.
Screw the outer barrel into its stabilizer (counter clockwise thread), leave a slight gap between the barrel and the stabilizer; if you tighten it all the way down, the front sight will go on upside down. With the barrel placed correctly (chamfers in the barrel on the bottom side, aligned with the gap on the stabilizer for the wiring), tighten down the set screws on the stabilizer.
The next step is a dry fitting of sorts. Place the outer barrel assembly into the front of the gun, and slide the threaded delta ring over it and tighten it down. If you have a front wired gun, route the wires appropriately, so that it doesn't get scarred up by the delta ring.
Now check the outer barrel for wobble. If it does wobble, check to see if the delta ring is hitting the mock gas tube. If the ring is hitting it, that steel bar (the mock gas tube) will need to be filed down, so that the ring can properly secure the outer barrel assembly. I used a bench grinder for this.
Once the barrel is secured, put on the handguard. It is threaded clockwise.
Next, you can install the front sight. Slide it into place, and punch the pins in with a hammer. Now add the front sling hook the same way.
Lastly you can put on the flash hider. Screw it on (counter clockwise thread) and tighten the grub screw.
That's it the install is complete.
The parts of the JBU free Float kit are all well made, and the install is super easy. Fit and finish is excellent on nearly all the components, and the checkering on the grip is well done. While the handguard is a real pain in the posterior for front wired guns, it looks wicked.
- Looks great
- Easy install
- High quality parts
- Battery issues
- May require permanent modification to the "gas tube"
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