I wanted to do a review of the ICS upgrade gear box package E. This is a preliminary review of the initial installation and performance of this ICS kit. For those who want to know "what if i use a Guarder this, or a Prometheus that" this is not the point of this review as it is a review of a kit meant only for an ICS M4 made by ICS.
This is the gear box package that i installed. It retails in Canada for $149 and comes with all parts to make a complete upper gear box with no need to purchase anything except lube. This particular version comes with a full capacity cylinder, silent head set, metal spring guide with bearing and aluminum piston. The spring is supposed to be an m120, but more on that in a bit. The upper assembled with little problem except with regards to the spring. I noticed how strong this spring was and came to the conclusion that this is no m120. It was just as strong IMO as the 190% PDI springs i have worked with in many G&P M4's. After assembly of the upper gear box, i proceeded to remove the lower from my M4 to install bushings that would now be up to the task of a new upper.
With lower mods complete, i proceeded to install the upper in my M4, which is the best part of this upgrade. All that is required is to remove the rear receiver pin and flip up the upper receiver. The upper gear box simply slides out (a little tight though) and you slide in the new upper gear box. It should be mentioned that you should depress the forward assist button and remove any spring tension prior to opening the gun to avoid any piston damage and make your life much easier. With the upper gear box installed you simply close the gun, making sure that the sector gear is set for gear box closure with no piston teeth engaged. This procedure is also shown in the owner's manual for the gun. Once the gun is closed, you just re-install the rear receiver pin and the gun is now ready to fire. If you have the completed upper readily assembled, changeout can be done in less than 1 minute. So you can have a stock gun, or an upgraded gun, with only 1 minute of your time to chose which one you want.
Now that the gun was ready to fire, i dry fired a few times to check functionality. I immediatley noticed a reduced rate-of-fire, as would be expected with a new, stronger spring. I immediatley loaded up a mag with .20g bb's and proceeded to test the gun. WOW!! i was pleased to see the increase in fps this new upgrade delivered, as it punched through a double layered cardboard box on both sides and broke the finish on the door behind the box (sorry, honey). I grabbed the chrono, (which is a paintball radar and not the most accurate, but later i will get the team IR chrono for more accurate results) and tested the gun. The upgraded upper produced fps ranging from 388 to 396 at 15 degrees C with AE .20g bb. I emptied one TM lo-cap and stopped to change the upper back to stock and check the stock velocity. The stock upper generated fps ranging from 285 to 301 fps, which is a low number many ICS owners can attest to and due inpart to the type of chrono used and temperature in my shop. When i use the team chrono later this week, i'll update my results.
My overall impressions of this upper gear box kit are very good, but the one thing that does concern me is the spring. Many companys will put a value on their spring which does not necesarily conform to any fixed guidelines and can be difficult to gauge without a trial. IMO i think this spring is a little "too hot" for this particular arrangement, as i estimate that velocities will probably be about 430ish in real world summer use. I would recommend a downgraded spring to keep velocities in the 380 area and keep your gun happy.