The AR is a system. Change one thing, something else is affected.

 

For example - NiB/boutique bolts. They allegedly run cooler with less fouling. Great!

 

Except the gun is still producing the same amount of heat and carbon regardless of what the bolt is made of or coated in. That extra fouling and heat has to go somewhere. So now the barrel extension, barrel, upper receiver, barrel nut, gas block, and gas tube get dirtier and/or hotter than designed - instead of the the part designed to sink the heat and bleed it off and is removable to clean better and easier - the BCG.

 

There is no free lunch.

Thanks.

The bolt and bolt carrier group,

 

Very few companies make a bolt, but many "companies" "sell bolts".  Extractors are very important but they are not all made the same.  Some companies say their bolt is mil spec, but not ALL the parts are mil spec.  Same with just the carriers and carrier groups. 

 

http://www.monmouthreloading.com/shop/toolcraft-bcg/

 

Save yourself money and buy from the source.  If you need a name brand, write whatever you like on it with a sharpie, haha.