Intro: Bolt Action K'nex ACR
Here are some pictures of my ACR replica. It is true bolt action, so will fire hard and far, with removable, internal pusher magazines. It also looks very accurate (although some dimensions have been slightly tweaked to gain the best performance from the weapon), and handles very well, although it is slightly front-heavy, due to the complex ramp mechanism for the bolt action coupled with a lightweight hollow stock. The stock could be filled in to counterbalance the front-heaviness, but I have tried this and prefer the overall weight reduction to the perfect balance. The iron sights are also very close to the actual weapon's.
The overall mechanism was taken from my F2000, however this has a working mechanical trigger (rather than the rather disappointing and botched string trigger than put so many off building it) and the location of the bolt in this design is much more practical and ergonomic than the F2000. There is also a sophisticated mag release lever which can be operated without taking a finger off the trigger, as indicated in the slideshow.
To summarise, it is lighter, easier to handle, is easier to use, and is more accurate than my F2000. It also has a trigger.
Yet again, some credit to Ironman69 for the mag pusher idea.