Like I said in a prior post and as explained more thoroughly by Big Country Expat, the Bolt Carrier Group or BCG, is probably the most important moving part on an AR-15 and it is one item you should have at least one spare.
It is also kind of pricey.
With that in mind I want to pass on a deal, and please note I have no affiliation with this company and get no compensation, on a BCG. It comes from Ballistic Advantage and is their phosphate M16 5.56 BCG. The regular price is $125 but if you use code NEW10 you get 10% of on your order. Plus it is free shipping and they don’t appear to charge sales tax if you are not in their state. I already had one of their BCGs as a spare but I need another one so I ordered it today and all in it was $112.50. That is about as good a deal as you will get on a quality BCG and they actually have them in stock, another bonus.
This is a pretty good price especially considering the free shipping so get you one or three.
* Update *
I ordered the BCG at 4:00 PM EST yesterday (3/4/21) and it shipped at 9 AM this morning (3/5/21). That is outstanding in this environment.