How do you guys think they compare to Colt bolts?

TIA

In terms of function,  I don't think there is much difference.
The Colt has better machining , smooth around the lugs & bolt face (no milling marks) and Colt is marked MPC so you know that it has been inspected for quality control.  
The last Colt bolt that I bought has a copper colored extractor spring with black insert  that is supposed to be an improvment.
The bolt is the heart of the AR and takes all the stress from firing,  so it's important to be sure you get a good one.  I use Colt
bolts in my rifles,  because of the markings and machine work,  I know that what I receive is what I paid for.
I don't know what quality control Bushmaster does,  I've not heard of any problems with them
but they look just like all the rest of the unmarked bolts out there.

Does anyone know for certain if Bushie MP or proof tests their bolts?

Ditto Stickman's question, anyone?

i think bm tests examples from lots, not every bolt