New AR on the horizon

[Tater]

So I've decided on a new "evil black rifle" with my tax return, but I want one I can upgrade/change easily. I'd like to have one that I can buy a few different uppers for, easy to change buttstocks, new furniture, sights, scopes, etc. I've heard some (Colt) you have to buy from the same manufacture and I don't want that. I've seen some DPMS and Stag Arms ARs for good prices...how are they with new parts? How are the other AR manufacturers for new/upgrade parts? Any opinions are welcome. Thanks

[Skinny Shooter]

Are you referring to Colt large pin Uppers?
Question #3 at this link addresses that issue: http://cheaperthandirt.com/blog/?page_id=96

Check out this link which has a link to what was known as "the chart".
It was a comparison chart of all major brands.
http://www.m4carbine.net/showthread.php?t=6642

The actual chart is offline but there are still a lot of details to read up on.
Brownell's has some AR gunsmithing videos on their website.

At this link are several versions in photos of "the chart".
https://www.google.com/search?hl=en&client=safari&tbo=d&biw=1024&bih=672&tbm=isch&sa=1&q=ar+15+the+chart&oq=ar+15+the+chart&gs_l=img.3..0i24.4905.6812.0.7237.6.6.0.0.0.0.122.610.2j4.6.0...0.0...1ac.1.2.img.NlCMtSHXAFo

[muledeer]

I have a Bushmaster XM E2 (AR-15). I also have a Colt upper and it is interchangeable with the Bushmaster lower.
muledeer