Difference point with pure barrel 1
The function to have omitted part is provided in consideration of the cost performance.

"Hole that fixes front sight"

Past M4 did not have the screw. We canceled it, because we had judged that there was no problem in past method for fixing.

Difference point with pure barrel 2

The position of the nut was made to be advanced a little in consideration of shaking of the hand guard in the state not remodeled. As a result, the rigidity rises and the fit feeling is improved.

M3 screw that cannot be confirmed

The M3 screw on the reception desk side doesn't understand the usage as of July, 2009.It can be guessed that it is a hole to fix PEQ, RIS , and RAS, that will be put on the market in the future. But we cannot say it is certain. Therefore, please understand that It cannot be asserted that it is possible to correspond to The development in the future.

A considerable technology and the knack are necessary to take M4 faction apart. The maximum problem is "Difficulty of taking the around the neck apart. Whether this "Barrel lock ring" can be removed is a point. Though it is unconfirmed, it seems to be easy to remove the M4 series since second lot comparatively. Though we make and opened a special wrench...

Then, the ring came to come off. However, it is not possible to be relieved still for a while.
If power is put too much, it is transformed because the lock is forcibly released.
The important one is "Barrel lock ring" and "barrel base".

"Barrel lock ring"	"Barrel base"

These influences the strength of the main body and the barrel directly. When these are transformed, strength around the neck is lost, and It becomes impossible to return to original as long as parts are not exchanged. Please do carefully. It might be transformed even if it does carefully.
Because there is no strength in the material.
Especially, because barrel base is made by zincky and has no thickness, it is transformed indeed often. It produces it later because it is thought that the custom parts are necessary for this.

Next, please note "barrel nut" related to the fixation of the hand guard.
The M3 screw to fix the nut of the real outer barrel that PDI made, the position is adjusted.
As a result, the hand guard side is cut down because it rubs against the nut when the hand guard is set.
However, trouble is not caused by this wear-out. It was able to become easy to insert.

When there is no strength on the neck:
When there is no strength on the neck by the transformation and damage, the method of placing a thin spacer between barrel base and barrel lock ring is effective. Some shaking can be decreased by doing so.

When you cannot install the front sight well:
The ditch for the site is cut down a little shallowly.
Please cut down thinly with round stick file when feeling that tightness.
It is more effective that the inside diameter of the front sight is cut down with the emery paper.