I have a MGI modular lower and QCB upper. It is as rugged and reliable as either of the other 2 AR's I own, both of conventional design. With the 16" Bushmaster barrel it outshoots my standard CAR. I have beat the heck out of mine, and it keeps ticking. I also shoot 458 SOCOM through it. Now that round does kick a bit, yet the upper and lower are no worse for wear. I like it so much I'm planning on getting a second upper, and the .308 conversion for it. Probably going to sell off my other AR's.
I'd attach pictures, but I'm deployed right now supporting training.
The guys who run the company, the Gwinns, are some of the friendliest and most knowledgeable folks in the business.
For more info on this, use this link:
More info on the MGI Upper and Lower.Tom Lyons is their rep, and he's a hell of a good guy. I'm sure he'll be posting here shortly with specifics.
Hope this helps.