I think I can vouch for the quality of our lower receivers. To date, I have not received a single request for replacement of a cracked lower. I'm sure they are out there, as indicated by the above reply, but I think a lot of our valued customers can attest to the quality of our lowers.
Regarding the bevel gear, we received acknowledgment from ICS that a isolated batch of bevel gears had a minor tolerance issue, resulting in premature slipping of two pressure fitted components.
This did strike me as odd, as we had never encountered or heard of this being a common or persistent problem. We have replaced any and all bevel gear issues that have been presented to us. Literally, a quick 10 minute fix on the M4 platform.
Haven't had a single call back since our latest shipment arrived, so it seems this bogus batch of bevel gears are past us. Nice to see a manufacturer step up, and get the problem resolved asap.
Regarding pistons, be aware that the majority of these isolated piston breaks are a result of users using the "spring release" mechanism incorrectly. Most AEG's have a fake one, and is not functional. ICS M4's is actually a functional one, and should "ONLY" be used after having fired off 2-3 single shots immediately following a full-auto burst. Firing in full auto will at times leave the spring cocked back, and under considerable pressure, and depressing the spring release button will cause a very aggressive and possibly damaging collision between the gear and piston teeth. This can contribute to the piston teeth cracking.
By firing 2-3 single shots after full-auto, you essentially reset the gears and position of the piston in to the correct alignment. At that point it is safe to press the spring release button. Do that and you will all but eliminate the possibility of breaking piston teeth
Alot of people think it's cool to press buttons and hearing stuff go on inside their guns. This feature is intended to be used if you need to crack your gun open for service, or if you are storing for a prolonged period of time. Other than that, leave that button alone.
You will have no problems with your M4 otherwise.