I picked up an ACR last friday and thought I'd share my observations and outlook on the rifle. The ACR comes packed in a larger hunting style plastic case with 1 - 10 round mag, front and rear Magpul plastic BUIS and a very well done and thorough instruction manual. The receiver also has a monolithic rail that runs to about 2" from the gas plug. This is a NY compliant rifle (yes, they're already pandering to our commie state market), which gets their birdcage style compensator and the fixed stock. The rifle I ordered was the basic version with only an adjustable cheek piece and not telescoping stock. AKA - NY compliant.
Fit and finish is unlike any new production rifle I've seen in a long time. The ACR was produced without any of the problems noted at SHOT last year. The ACR has near perfect machining, inside and out. The plastics are soft, lacking in mold marks and perfectly finished. The rifle also has a plethora of attachment points or slings already built in. There are quick detach points on the front and rear on both sides and a single point mount, which is reversible on the left side. The adjustable cheek piece has two positions, up and down. Up allows a more centered look down the standard AR15 height mounts. The down position is the natural position for the ACR, regardless of the height of the sights that come with the ACR. All machining is top notch. No real noticeable swirls or rough edges anywhere, except around the bolt. But it looks almost like jeweling swirls, rather than bad machinework. All metal around these tracks are perfect, so I'm assuming this was designed into the ACR rather than overlooked or left unfinished. It's very very well done.
The balance and feel of the ACR are in my opinion, the best off the shelf for a rifle that I've felt in awhile. It's a bit heavier than a standard AR15, but I'm guessing that's because of what I'm guessing is a heavier grade of plastic. Compared to the closest competitor, the SCAR, this rifle is much nicer in the quality of it's components. The only thing the SCAR has is better BUIS sytem. I like the magpul plastic sights as a cool bit of kit, but they wouldn't be my first choice. Or second.
The ACR also comes apart much easier than most other rifles. The way it breaks down is similar to a couple of different rifles. It has some AR15, some H&K and a feel of the AR180 in the internals. Speaking of which, it has a nice trigger, which uses an AR15 trigger group in it's own modular group. I'm guessing you'll be able to get a second block to put another trigger group in in the future.
Controls are ambidextrous with the mag release in the normal AR15 spot and the bolt release is just behind the magwell, which is activated by pushing down. It's a bit stiff, but I'm guessing it breaks in. The POTENTIAL for modularity is definitely there and waiting. The lower can be swapped out, the barrel can be swapped out and it's very easy to do anything with this platform. I've already taken the barrel off and it reinstalled easily. Anyone could do it effortlessly.
Take down involves pushing 4 pins. The stock slides up out of the lower, the hand guard slides forward and off and the BCG slides out of the rear ALA AR15/AR180. It comes apart completely, including the barrel in less than a minute once you've done it the 1st time. Reassembly takes even less time.
Accuracy is phenomenal! I got down to the range and put about 4 mags through it from the bench using an Aimpoint Comp M4s. At 100 yards, my M193 held 1" groups. Using a 0x optic, this was impressive - for ME. I'm bringing a Mark IV out next time to test it's limits of accuracy. The ACR was also similar to any gas piston AR on the market right now. The comp worked well, but considering the caliber, it's no biggie anyway.
I'm going to try and upload some pics tomorrow. But I don't have a ton of crap hanging off of it. A scope and the BUIS is all I wanted on it. I don't believe that 120 rounds is sufficient to test the reliability, but there were no problems at all. This platform is only supposed to get better as Bushmaster provides extra barrels and calibers supposedly 1Q to 2Q of 2011. This is in stark contrast to the SCAR's lack of support by fn.
Anyway, the main thing to take away from my review is that you MUST handle this rifle. I believe it's the beginning of a new standard in rifles. I'm that impressed.