Originally Posted by AKAMrWraith
Just throwing it out there but what about the G&G can soft M4, heard good things about them in exception to the terrible piston head.
I bought one of the standard G&G M4's as part of a rental package I'm putting together for some friends.
Compression/air seal issues aside, out of the box they're not bad. If all you plan to do is use one in stock trim they'll get the job done. However, they're a poor choice as an upgrade platform.
The dimensions on the G&G differ from most other M4's on the market. I needed to purchase a new delta ring and end cap just to install a Magpul MOE hand guard properly. Once that was done, the gas tube no longer lined up with the upper receiver port; out comes the dremel. The mechbox itself is okay and should be able to take just about any aftermarket part. The same can not be said of the hop-up unit.
The retention slots on the chamber block of the G&G outer barrel are made for the G&G unit only. Although the hop-up looks like a standard M4 unit, the mounting tabs on either side are thinner than an aftermarket one, meaning most hop-up units will not fit without modification, or a change of outer barrels. Top all this off with the fact that the G&G upper does not mate (without modification) to standard metal lowers.
As stated above, if you just want something that shoots, the G&G will fill that role. If you want to get fancy and upgrade the snot out of it...don't bother. Not that it can't be done, but it's just not worth the time and effort.