My basic rationale for choosing a TM MP5k to tinker with is primarily because it is cheap, hell I've seen it for less than $200 in some places. I've heard of people sticking some systema parts, an EG1000 motor, and a M100 spring into an MP5K. I'm not necessarily looking for a better sidearm, although that would be a good side effect of this project. I just want something that I can take apart, so that I can learn how to install upgrade parts for an AEG. I just don't wanna spend an arm and a leg for a $300 AEG, break it beyond repair since I'm a first timer, and lose a ton of money in the process.