So I built an ar sometime ago with donated parts from a friend. The most significant pieces being an A1 upper (fixed carry handle) and the "standard" bushmaster bcg. So I ended up getting a good deal on a BCM 20" barrel and made it an original M16 knock off. The novelty has worn off and I now wanna change out the upper receiver and get a free float handguard to build more of a precision ar.

My questions center around how important the bolt is to building an ar more intended for more precis shooting at 3-500 yard with a higher powered scope.
1. Would my run of the mill, non-MPI bushmaster bcg be good enough? I presume my barrel is of good quality for this purpose.
2. If I decide to splurge on a bolt because I convinced myself it will result in better accuracy, then would there be a point in getting a whole bcg? My cheap self wants to believe that a high dollar bolt body (excluding the head) won't add to accuracy. Just reliability with all the fancy coatings and checking options.

I've wondered about these things myself. I suppose you might gain durability and reliability, but in the end I conclude that spending the money on such stuff would be like buying precision thumbtacks.

My experience has been that AR bolts and barrel extensions are usually held to very tight tolerance for concentricity and specified dimensions. Most makers know that users may take a bolt and use it on multiple uppers without checking headspacing so they try and avoid any issues by holding as tightly as possible to acceptable consistent standards.

That's just my anecdotal experience from the many bolt, carrier croups, and barrels I've handled so others' experiences may vary.

The greatest variation in BCG quality usually has more to do with quality of materials. Many companies have, from time to time, cut costs by using substandard material and coatings on the bolt, gas key, carrier, springs, and extractors.

Depending on what phase BM was in when it made your BCG I doubt youll have any trouble with accuracy, and bet you're more likely to need to replace an extractor sometime down the road. Without looking at your bolt personally I couldn't make a judgment on that either since there were times when BM made everything just fine.

1. Yes
2. White oak makes barrels with a fitted bolt. That's where I would go with it.

Agree with this ^^^

Also suggest checking headspace if you make any changes. Unlikely there will be an issue, but all machined parts have variances and tolerances. In a conversation with a technician at AR15 Performance regarding their process to match a bolt (i.e. "fitted" bolt) with a barrel, he stated that they have so many bolts that they simply can try multiple until they find the desired fit with headspacing. To me, this confirms the variances and tolerance stack-ups.

Thanks for the feedback guys. I'm no ar so I just wanted to confirm my suspicions. Now I can spend moneys elsewhere on things I know will get my improved accuracy. You know, like a cerakote paint.

Don't forget the NOS sticker